The amount of the sample that has decayed in one hour is 1 grams
How do I determine the amount that will decay in one hour?First, we must obtain the number of half lives that has elapsed after one hour. This is shown below:
Half-life (t½) = 1 hourTime (t) = 1 hourNumber of half-lives (n) =?n = t / t½
n = 1 / 1
n = 1
Finally, we shall determine the amount remaining after 1 hour. Details below:
Original percentage (N₀) = 2 gramsNumber of half-lives (n) = 1Amount remaining (N) = ?N = N₀ / 2ⁿ
N = 2 / 2¹
N = 2 / 2
N = 1
Finally, we shall obtain the amount that has decayed in one hour. Details below:
Original percentage (N₀) = 2 gramsAmount remaining (N) = 1 gramAmount that decay =?Amount that decay = N₀ - N
Amount that decay = 2 - 1
Amount that decay = 1 gram
Thus, the amount that has decayed in one hour is 1 grams
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The numerical value of the equilibrium constant, Kc, for the following reaction is 1.7×102. If the equilibrium mixture contains 0.21 M H2 and 0.015 M N2, what is the molar concentration of NH3?
3H2(g)+N2(g)⇌2NH3(g)
The molar concentration of NH₃ is 0.17 M.
The equilibrium constant expression for the given reaction is:
Kc = [NH₃]² / ([H₂]³[N₂])We are given Kc = 1.7 × 10² and the molar concentrations of H₂ and N₂ in the equilibrium mixture as 0.21 M and 0.015 M, respectively. Let x be the molar concentration of NH₃ at equilibrium. Then, we can write:
Kc = (x)² / (0.21)³(0.015)1.7 × 10² = x² / 1.84 × 10⁻⁶x² = 3.128 × 10⁻⁴x = 0.017 M or 0.17 M (since there are two NH₃ molecules produced for every three H₂ molecules consumed, we take the square root of the calculated value to get the molar concentration of NH₃)
Therefore, the molar concentration of NH₃ in the equilibrium mixture is 0.17 M.
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What is the density (in g/L) of CO2 in a 5.20 L tank at 760.0 torr and 39.0°C .
The tank's CO₂ density is 1.84 g/L.
How to calculate density?Use the ideal gas law to solve for the density of CO₂:
PV = nRT
where:
P = pressure = 760.0 torr
V = volume = 5.20 L
n = moles of CO2 (we don't know this yet)
R = gas constant = 0.08206 L·atm/K·mol
T = temperature = 39.0°C + 273.15 = 312.15 K
First, convert torr to atm:
760.0 torr ÷ 760 torr/atm = 1 atm
Rearrange the ideal gas law to solve for n:
n = PV/RT
n = (1 atm)(5.20 L)/(0.08206 L·atm/K·mol)(312.15 K)
n = 0.217 mol
Use the mass of CO₂ and the volume of the tank to find the density:
mass = n × molar mass
mass = 0.217 mol × 44.01 g/mol
mass = 9.57 g
density = mass/volume
density = 9.57 g/5.20 L
density = 1.84 g/L
Therefore, the density of CO₂ in the tank is 1.84 g/L.
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Select the correct answer. What effect does increasing the temperature have on a reaction? A. The rate constant and reaction rate are both decreased. B. The rate constant and reaction rate are both increased. C. The rate constant is increased and the reaction rate is decreased. D. The rate constant is decreased and the reaction rate is increased.
Answer:
The correct answer is B
Explanation:
The rate constant and reaction are both increased
A chemist wants to make a 17.85 %(m/m) solution of NaCl using a only 50.0 g of the salt. How much water is needed to make the solution? Numerical answer only. No units.
The mass percentage is an important method which is used to calculate the concentration of a solution. The amount of water needed to add in order to make 17.85 % NaCl solution is 230.1 g.
What is mass percentage?The mass percentage of a component in a solution is defined as the mass in grams of that component present per 100 g of the solution. The term mass percentage is denoted as w/w. It is used to calculate the concentration of a binary solution.
Mass percentage = Mass of the component in the solution / Total mass of solution × 100
17.85 = 50.0 / 50.0 + x × 100
0.1785 (50.0 + x) = 50.0
8.925 + 0.1785 x = 50.0
0.1785 x = 41.075
x = 230.1 g
Thus the amount of water added to make the solution is 230.1 g.
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Please help 100 points can be made. And first answer would be marked brainiest.
Write what you know about chemical reactions in living things.
Answer:
Chemical reactions in living things are the chemical processes that occur within living organisms to maintain their biological functions. These reactions are essential for metabolism, growth, reproduction, and response to stimuli. They involve the conversion of one or more substances into new substances with different physical and chemical properties.
Some examples of chemical reactions in living things include:
Cellular respiration: the process by which cells convert nutrients into energy in the form of ATP. This process involves the oxidation of glucose to produce carbon dioxide, water, and ATP.
Photosynthesis: the process by which plants and other organisms convert light energy into chemical energy in the form of glucose. This process involves the conversion of carbon dioxide and water into glucose and oxygen.
Digestion: the process by which food is broken down into simpler substances that can be absorbed and used by the body. This process involves the hydrolysis of complex carbohydrates, proteins, and lipids into simpler molecules such as glucose, amino acids, and fatty acids.
DNA replication: the process by which cells make copies of their DNA before cell division. This process involves the synthesis of new strands of DNA from existing strands.
Chemical reactions in living things are regulated by enzymes, which are biological catalysts that speed up chemical reactions by lowering the activation energy required for the reaction to occur. Enzymes are specific to particular substrates and are critical for the proper functioning of metabolic pathways. Any disruption in these chemical reactions can lead to metabolic disorders and diseases.
Explanation:
2 Pretest Unit 5 Question 22 of 30 Why are there so many carbon-based compounds? O A. Carbon can form compounds with any other element in the periodic table except noble gases. OB. Carbon can form up to six bonds with other carbon atoms and atoms of other elements. OC. Carbon can form single, double, or triple bonds and can bond with itself and other elements. D. Carbon can form ionic, covalent, and metallic compounds under the right conditions. ZA
The why there are so many carbon-based compounds is that B. Carbon can form up to six bonds with other carbon atoms and atoms of other elements.
What is the uniqueness of carbon?Carbon can be described as the element that posses 4 electrons in its outermost shell, and it has the asbility to gain or loss 4 electrons to so it can have nobel gas configuration.
It should be noted that Catenation is one of the unique ability of carbon which help it to form bonds with other atoms of carbon and due to this reason, it have the ability to record a long chains of different types of compounds.
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20. Using the equilibrium expression from Question #19 and based upon the value of K, would you expect there to be more or less product in the equilibrium mixture? Explain why.
The value of K is given as 2344 thus more products are obtained at equilibrium since the equilibrium constant is very large.
The equilibrium constant ( K ) is equal to the rate constant for the forward reaction divided by the rate constant for the reverse reaction.
The balanced equation is -
CaO(s) + CH₄(g) + 2H₂O(g) —> CaCO₃(s) + 4H₂(g)
K = [CaCO₃] [H₂]⁴ / [CaO] [CH₄] [H₂O]²
Since the value of K = 2344, which is large, more of products will be formed in the reaction.
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How is the kinetic energy of the particles of a substance affected during a phase change?
• Kinetic energy increases during exothermic changes and decreases during endothermic changes.
• Kinetic energy decreases during exothermic changes and increases during endothermic changes.
• Kinetic energy does not change, but the potential energy does.
• Kinetic energy changes in the opposite way that the potential energy changes.
The kinetic energy of the particles of a substance affected during a phase change is Kinetic energy does not change, but the potential energy does.
What is phase change?A phase change can be described as the physical process whereby the substance can be transformed from one phase to another.
It should be noted that the change do take place in a case whereby you are adding as well as removing heat which can be considered as melting point or the boiling point of the substance and this can be understood using phase change.
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The activation energy, Ea, for a particular reaction is 37.8 kJ/mol. If the rate constant at 280 K is 0.178 M/s, then what is the value of the rate constant at 381 K? (R = 8.314 J/mol • K)
The rate constant that we have at 381 K will be 2.19 M/s.
What is the Arrhenius equation?The Arrhenius equation suggests that the rate of a reaction increases with temperature, because higher temperatures provide more kinetic energy to the reactant molecules, making them more likely to react.
By the use of the Arrhenius equation, we have that;
ln k2/k1 = -Ea/R(1/T2 - 1/T1)
ln k2/0.178 = -37.8 * 10^3/8.314 (1/381 - 1/280)
ln k2/0.178 = - 4647 * (2.62 - 3.57) * 10^-3
lnK2 = 0.786
k2 =e^0.786
k2 = 2.19 M/s
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Can anyone please name this compound?
Answer:
Fluorobenzene
Explanation: Fluorobenzene is an organic compound, which is a derivative of benzene. It has a fluorine atom attached to one of the carbon atoms in the benzene ring. It appears as a colorless liquid and has a slightly sweet odor. Fluorobenzene is used as a solvent and catalyst in various chemical reactions. It is also used in the production of agrochemicals and pharmaceuticals. Due to its high solubility in water, it can contaminate groundwater and pose a risk to human health and the environment.
8. Base your answer to the following question on the equation below.
2H2(g) + O2(g) → 2H₂O()+571.6 kJ
Identify the information in this equation that indicates the reaction is exothermic.
The positive value of 571.6 kJwhich is the enthalpy change tells us that it is exothermic
What is an exothermic reaction?When energy is released into the surrounding area during a chemical reaction, it's considered an exothermic reaction with ΔH < 0. Conversely, endothermic reactions result from heat absorption with ΔH > 0.
The provided equation's positive value of 571.6 kJ reveals that heat is pouring out of the reaction, causing negative changes in enthalpy and firmly placing this chemical event as exothermic in nature.
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Read the passage and answer the question.
In 2000, when paleontologist Paul Sereno led an expedition into Ténéré desert in Niger looking for the fossils of dinosaurs and ancient crocodiles, the photographer Mike Hettwer wandered away from the group to take pictures of some dunes near the main dig site. The photographer quickly found bones sticking out of the dunes, but they were human bones, not the prehistoric reptile bones the group had been looking for. However, the group was not going to pass up such an amazing discovery.
During the site excavation, the paleontologists found dozens of gravesites. Some of them held skeletal remains and potsherds with wavy lines etched in them. The scientists named this group the Kiffians. The others held skeletal remains that indicated a taller group of people, and their potsherds were decorated with patterns of dots. The scientists named this group the Tenerians. The graves also contained tools and beads made from stones or bones, as well as refuse heaps containing the bones of the animals the people living in the area had consumed. Some of the graves didn't contain any pottery so it was a mystery which group they belonged to. It was also not known when these people lived in the desert or how they survived.
The carbon-14 dating revealed that the Kiffians lived in the area around 9,700 years ago, and then the area was abandoned until the Tenerians lived in the area 7,000 years ago. The scientists want to reconstruct what the land looked like when it was inhabited, as well as understand why there was about a 2,000-year-gap during which nobody lived in the area.
The scientists hypothesize that the two civilizations lived around a lake that dried up during periods of drought and then eventually reformed. The changing lake led people to move, depending on if they had a water source or not.
How can scientists use radiometric dating to reconstruct the geologic history of the area to support or reject their hypothesis of a disappearing and reappearing lake? What is a tool that scientists can use to ensure that their radiometric dating is accurate?
Answer & Explanation:
Scientists can use radiometric dating to reconstruct the geologic history of the area and support or reject their hypothesis of a disappearing and reappearing lake by analyzing the sediments and other geological features present in the area. Radiometric dating, such as carbon-14 dating, can determine the age of the sediments, fossilized remains, and other materials. By analyzing the age and composition of these materials, scientists can track changes in the environment over time, including periods of drought or increased precipitation that could cause a lake to dry up or reform.
To ensure the accuracy of their radiometric dating, scientists can use calibration methods, such as cross-dating with other dating techniques like dendrochronology (tree-ring dating), or comparing their results with well-dated samples from similar or nearby environments. This can help validate the radiometric dating results and provide more confidence in the reconstructed geologic history and any conclusions drawn from it regarding the presence or absence of a lake in the area at different times.
ties there khat is Chemical Compound?
Answer:
In chemistry, a compound is a substance made up of two or more different chemical elements combined in a fixed ratio. When the elements come together, they react with each other and form chemical bonds that are difficult to break.
Explanation:
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.453 mop of a gas confined to a 15.0 L container exerts a pressure at 125.6 kPa on the walls of the container. What is the temperature of the gas?
The temperature of the gas can be gotten from the ideal gas equation as 229.7°C.
What is the ideal gas law?PV = nRT
where:
P is the pressure of the gas in units of pascals (Pa)
V is the volume of the gas in units of cubic meters (m³)
n is the amount of substance of the gas in units of moles (mol)
R is the ideal gas constant with a value of 8.314 J/(mol·K)
T is the absolute temperature of the gas in units of kelvins (K)
We know that;
PV = nRT
Then;
T = PV/nR
T = ?
P = 125.6 kPa or 1.24 atm
n = 0.453 moles
R = 0.082 atmL/K-1mol-1
Then;
T = 1.24 * 15/0.082 * 0.453
= 18.6/0.037
= 502.7 K or 229.7°C
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In a coffee-cup calorimeter, 130.0 mL of 1.3 M NaOH and 130.0 mL of 1.3 M HCl are mixed. Both solutions were originally at 21.8°C. After the reaction, the final temperature is 30.5°C. Assuming that all the solutions have a density of 1.0 g/cm^3 and a specific heat capacity of 4.18 J/°C · g, calculate the enthalpy change for the neutralization of HCl by NaOH. Assume that no heat is lost to the surroundings or to the calorimeter.
H = ? kJ/mol
The heat capacity of a substance or system is defined as the amount of heat required to raise the temperature through 1°C. It is an extensive property and its value depends on the quantity of matter present.
The heat needed to raise the temperature of 1 gram of the substance through 1°C is the specific heat capacity.
Heat required is:
q = mc (T₂ - T₁)
m = V × ρ
q = (130 + 130) × 1.0 × 4.18 ( 30.5 - 21.8) = 9455.16 J
9455.16 J = 9.45516 kJ
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In the following reaction, what quantity in moles of CH₃OH are required to give off 6106 kJ of heat?
2 CH₃OH (l) + 3 O₂ (g) → 2 CO₂ (g) + 4 H₂O(g) ∆H° = -1280. kJ
To generate 6106 kJ of heat, 9.5 moles of CH₃OH are required.
The given reaction releases -1280 kJ of heat. We need to find how many moles of CH₃OH are required to release 6106 kJ of heat.
From the given balanced equation, we know that 2 moles of CH₃OH releases 1280 kJ of heat.
Therefore, 1 mole of CH₃OH will release 1280 kJ / 2 = 640 kJ of heat.
To release 6106 kJ of heat, we can use the following proportion:
2 moles CH₃OH / 1280 kJ = x moles CH₃OH / 6106 kJ
Solving for x, we get:
x = (2 moles CH₃OH x 6106 kJ) / 1280 kJ = 9.5 moles CH₃OH
Therefore, 9.5 moles of CH₃OH are required to release 6106 kJ of heat.
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Exoplanets are usually....
O big, bright and close to the sun.
O gigantic, fireballs that are close to the sun.
O not a planet.
O small, dark, and far from the sun.
Exoplanets are usually gigantic, fireballs that are close to the sun. Therefore, the correct option is option B.
Any planet outside of our solar system is an exoplanet. The majority of exoplanets orbit other stars, while rogue planets—free-floating exoplanets that are unattached to any star—orbit the galactic centre.
The majority of the exoplanets found so far are in the Milky Way, which is a rather tiny area of our galaxy. The Kepler Space Telescope of NASA has revealed that the galaxy has more planets than stars. Exoplanets are usually gigantic, fireballs that are close to the sun.
Therefore, the correct option is option B.
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105.0 mL of alcohol is dissolved in water and the solution is diluted to a
total final volume of 250 mL. What is the final concentration of ethanol?
105.0 mL of alcohol is dissolved in water and the solution is diluted to a total final volume of 250 mL the final concentration of ethanol in the solution is 0.00722 M.
To calculate the final concentration of ethanol in the solution, we need to know the amount of ethanol present in the solution before and after dilution. We can use the following formula to calculate the final concentration:
Cfinal = Cinitial x (Vinitial / Vfinal)
where Cinitial is the initial concentration of ethanol, Vinitial is the initial volume of the solution, Vfinal is the final volume of the solution, and Cfinal is the final concentration of ethanol.
First, let's find the initial concentration of ethanol in the solution. We know that 105.0 mL of alcohol is dissolved in water, but we don't know the concentration of the alcohol.
Let's assume that the alcohol is pure ethanol (which is not always the case in reality), which has a density of 0.789 g/mL at room temperature. Therefore, the mass of ethanol in 105.0 mL of alcohol is:
mass of ethanol = volume of alcohol x density of ethanol
= 105.0 mL x 0.789 g/mL
= 82.845 g
The molar mass of ethanol is 46.07 g/mol, so the number of moles of ethanol in 82.845 g of ethanol is:
moles of ethanol = mass of ethanol / molar mass of ethanol
= 82.845 g / 46.07 g/mol
= 1.797 mol
The initial volume of the solution is 105.0 mL, so the initial concentration of ethanol is:
Cinitial = moles of ethanol / initial volume of solution
= 1.797 mol / 105.0 mL
= 0.0171 M
Now, let's calculate the final concentration of ethanol. We know that the final volume of the solution is 250 mL. Using the formula above, we get:
Cfinal = Cinitial x (Vinitial / Vfinal)
= 0.0171 M x (105.0 mL / 250 mL)
= 0.00722 M
Therefore, the final concentration of ethanol in the solution is 0.00722 M.
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1b. Suppose that you were titrating a 100 mL acid solution with the 0.1 M NaOH solution that you made. You performed the titration multiple times and obtained the data below. Complete the data table below. Show work on a separate piece of paper/ the back of this paper.
Step 1: Write and balance the chemical equation (only need to do this once for each titration)
Step 2: Use the molarity and mL of base used to find the moles of base it took to neutralize the acid
Step 3: Calculate moles of acid neutralized
Step 4: Calculate molarity of acid
Step 5: Calculate pH
1c. Calculate the most likely pH of the acid solution by finding the average of all the pH's you found in each of your multiple titrations. We find the average to minimize human errors made while titrating.
The moles of NaOH used is 0.0008 moles
The molarity of the acid is 0.008 M
What is the molarity of the acid?The molarity of the acid is found as follows:
Moles of NaOH used = concentration of NaOH × volume of NaOH used
the average volume of NaOH used = 8.0 mL
moles of NaOH = 0.1 M × 8.0 mL
moles of NaOH = 0.0008 moles
Molarity of acid:
Assuming the acid is monobasic, the mole ratio of acid to base is 1 : 1
The volume of acid used is 100 mL
The molarity of acid = moles of acid / volume of acid in liters
The molarity of acid = 0.0008 moles / 0.1 L
The molarity of acid = 0.008 M
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Why are Plinian eruptions more violent than Hawaiian eruptions?
OA. Plinian volcanoes have more viscous magma.
B. Hawaiian volcanoes are made of limestone instead of granite.
OC. Hawaiian volcanoes have less magma.
OD. Plinian volcanoes have stronger rocks.
We've figured out what part of the salt causes the flame to change color, so now let's measure the wavelengths created with four metals.
Use the ruler under the "tools" icon in the upper right of the video player to measure the wavelengths of light released by each compound.
Around 450 nm is the wavelength of the spectral line for potassium chloride. The distance among identical spots between two succeeding waves is known as the wavelength.
The distance among identical spots between two succeeding waves is known as the wavelength, which is a feature of waves. The wavelength of a wave is the distance across one wave's peak (or trough) and the next. In mathematics, the Greek symbol lambda () is used to denote wavelength. The colour of light is determined by its wavelength, and the pitch of sound is determined by its wavelength. Around 450 nm is the wavelength of the spectral line for potassium chloride.
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Determine the mass of 2.62 mol of iron(III) sulfate.
The molar mass of 2.62 mol of iron(III) sulfate is 1050.8 g.
Thus, the molar mass of iron(III) sulfate can be calculated by summing the atomic masses of its constituent atoms. The molar mass of a compound is the sum of the atomic masses of all the atoms present in a chemical formula of the compound which is then multiplied by the number of atoms of each element in the formula.
In iron(III) sulfate, the atomic mass of iron will be 111.70 g/mol. The atomic masses of Sulphur and oxygen will be 96.18 g/mol and 192.0 g/mol, respectively. Adding atomic masses of its constituent atoms will be 400.88 g/mol. Therefore, the molar mass of 2.62 mol of iron(III) sulfate is 1050.8 g.
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Magnesium (Mg) has nine electrons. Which of the following shows the correct electron configuration for an atom of Mg? 1, 8
The correct electron configuration for an atom of Magnesium (Mg) is 2, 7.
What is electron configuration?The distribution of electrons among an atom's or ion's energy levels and sublevels is referred to as electron configuration. It outlines how electrons are grouped in numerous shells and subshells surrounding an atom's nucleus.
The electron configuration is frequently expressed in shell and subshell notation, such as 1s², 2s², 2p⁶, 3s², 3p², where the numbers represent the energy level or shell and the letters s, p, d, and f represent the sublevels or orbitals inside each shell.
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How do characteristics of the planets,moons, and smaller objects in the solar system compare?
The planets, moons, and smaller objects in the solar system have several characteristics are; Size, Composition, Orbits, Atmosphere, and Evolution.
Planets are generally much larger than moons and smaller objects in the solar system. For example, the largest planet in our solar system, Jupiter, has a diameter of about 143,000 kilometers, while the Moon, Earth's natural satellite, has a diameter of about 3,474 kilometers.
Planets are typically made up of a combination of rock and/or gas, while moons and smaller objects can have a variety of compositions. Moons can be rocky, icy, or a mix of both, while smaller objects such as asteroids and comets can also have diverse compositions including rock, metal, ice, and other materials.
Planets and moons have different orbits around the Sun or their respective planets. Planets orbit the Sun in nearly elliptical paths, while moons orbit their parent planet in elliptical or nearly circular orbits.
Planets and some moons can have substantial atmospheres, while smaller objects in the solar system may have little to no atmosphere. For example, Earth has a dense atmosphere composed mainly of nitrogen, oxygen, and trace gases, while the Moon has no significant atmosphere.
Planets, moons, and smaller objects in the solar system have different origins and evolutionary histories. Planets are thought to have formed from the solar nebula, a cloud of gas and dust left over from the formation of the Sun. Moons can form throuugh various mechanisms, such as accretion, capture, or giant impacts. Smaller objects, such as asteroids and comets, are remnants from the early solar system and can provide valuable information about its history and evolution.
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Calculate the molar solubility, S , of CuS if it has a Ksp value of 6×10−37.
The molar solubility of CuS is 7.8 x 10⁻¹⁹ M.
The solubility product expression for CuS is:
Ksp = [Cu²⁺][S²⁻]Since CuS dissociates to form one Cu²⁺ ion and one S²⁻ ion, the molar solubility of CuS can be represented as x. Therefore, at equilibrium:
[Cu²⁺] = x[S²⁻] = xSubstituting these values in the Ksp expression:
Ksp = x²Solving for x, we get:
x = √(Ksp) = √(6 x 10⁻³⁷) = 7.8 x 10⁻¹⁹ MTherefore, the molar solubility of CuS is 7.8 x 10⁻¹⁹ M.
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The complete question is:
Calculate the molar solubility, S , of CuS if it has a Ksp value of 6×10⁻³⁷.
When you write the formula for sodium hydroxide, you do not have to put parentheses around the hydroxide polyatomic ion. However, when writing the formula for aluminum hydroxide, you must put parentheses around the hydroxide polyatomic ion. a) Write each formula. b) Explain why the parentheses are necessary for aluminum hydroxide.
(a). Sodium hydroxide: NaOH, aluminum hydroxide: [tex]Al(OH)_3[/tex]
(b). The parentheses are necessary for aluminum hydroxide because the hydroxide polyatomic ion has a subscript of 3, indicating that there are three hydroxide ions for every one aluminum ion.
a) The formula for sodium hydroxide is NaOH, and the formula for aluminum hydroxide is [tex]Al(OH)_3[/tex]
b) Aluminum hydroxide requires brackets because there are three hydroxide ions for every one aluminum ion, according to the hydroxide polyatomic ion's subscript of 3. Without the parentheses, it would be unclear whether the subscript of 3 applies to only the oxygen or to the entire hydroxide ion. By enclosing the entire hydroxide ion in parentheses and placing the subscript outside the parentheses.
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A sample of gas occupies 50.0L at 15.0 Cand 640.0 mmHg pressure. What is the volume at STP?
Answer:
2.00 L of a gas is collected at 25.0°C and 745.0 mmHg
Explanation:
Question 2 of 10
You read a primary source and a secondary source that discuss the same
experiment. There is a difference in the conclusions made by these two
sources. Which should you trust more, and why?
OA. The primary source, because it was written by the researcher
OB. The primary source, because it contains more charts
OC. The secondary source, because it was printed on paper
OD. The secondary source, because it is easier to understand
SUBMIT
It is the primary source which helps the students to relate in a personal way to events of the past and promote a deeper understanding of history as a series of human events. The primary source is better, because it contains more charts. The correct option is B.
The sources which are closest to the origin of the information and contain raw information which must be interpreted by the researches are called the primary sources. The secondary sources are closely related to the primary sources and often interpret them.
A direct access to the subject of our research is given by the primary source whereas the secondary source provides only second hand information and comments of other researches.
Thus the correct option is B.
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How much energy is required to heat 186 grams of water from 32 degrees Celsius to 90
degrees Celsius?
Trimethylamine is a weak base. A 0.150 M solution of trimethylamine has a pH of 11.5.
What is Kb for trimethylamine?
Kb for trimethylamine is 1.0 × 10^-2.5.
We can use the relationship between Kb and Ka for a conjugate acid-base pair:
Kb × Ka = Kw
The pKa is related to the pH :
pKa + pKb = 14.00
pKb = 14.00 - pKa
We can calculate the pKa using the relationship:
pH = pKa + log([base]/[acid])
Therefore, [base] = [acid], and we can simplify equation to:
pH = pKa + log(1)
Therefore, the pKa of trimethylammonium ion is 11.5.
Now :
Kb × Ka = Kw
Kb = Kw ÷ Ka
Since we know that Kw = [tex]1.0 * 10^{-14[/tex]and Ka =[tex]10^{-11.5[/tex] (from the pKa value we calculated earlier), we can substitute these values to get:
[tex]Kb = (1.0 * 10^{-14}) / (10^{-11.5}) = 1.0 * 10^{-2.5[/tex]
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