What is the pH of a solution made by mixing 0.050 mol of NaCN with enough water to make a liter of solution
Answer:
pH = 11
Explanation:
The equilibrium of a weak base as NaCN in water is:
NaCN(aq) + H₂O(l) ⇄ OH⁻(aq) + Na⁺(aq) + HCN(aq)
And kb, the equilibrium constant, is:
Kb = [OH⁻] [HCN] / [NaCN]
Where Kb of NaCN is 2.04x10⁻⁵
In the beginning, the [NaCN] is 0.050mol / L = 0.050M.
Both [OH⁻] and [HCN] are produced from this equilibrium, and its concentration is X, that is:
2.04x10⁻⁵ = [X] [X] / [0.050M]
1.02x10⁻⁶ = X²
X = 1x10⁻³ = [OH⁻]
As pOH = - log [OH⁻]
pOH = 3.00
And pH = 14 - pOH
pH = 11
In Fig 1-2, how should the length indicated by the arrow along the ruler be recorded?
Answer:
C. 0.35cm
Explanation:
The length indicated by the arrow along the ruler should recorded be recorded as "0.35cm".
This is correct because when counting the measurement on the ruler, the first line on the ruler is 0.1cm, the second line is 0.2cm, and so on. The spaces between each line is 0.05cm. So, the arrow is pointing on the space between 0.3cm and 0.4cm.
Therefore, 0.3cm + 0.05cm = 0.35cm.(answer).
How many valence electrons must a lithium atom lose to obtain a complete valence shell?
A. one
B. two
C. three
D. four
Answer:
C. three
Explanation:
Hydrogen sulfide decomposes according to the following reaction, for which Kc=9.30E-8 at 700 degrees Celsius. 2 H2S(g) --> 2 H2(g) + S2(g) If 0.29 moles of H2S is placed in a 3.0-L container, What is the equilibrium concentration of H2(g) at 700 degrees Celsius?
Answer: The equilibrium concentration of [tex]H_2(g)[/tex] at 700 degrees Celsius is 0.0012 M
Explanation:
Equilibrium constant is defined as the ratio of concentration of products to the concentration of reactants each raised to the power their stoichiometric ratios. It is expressed as [tex]K_c [/tex]
Moles of [tex]H_2S[/tex] = 0.29 mole
Volume of solution = 3.0 L
Initial concentration of [tex]H_2S[/tex] = [tex]\frac{0.29mol}{3.0L}=0.097M[/tex]
The given balanced equilibrium reaction is,
[tex]2H_2S(g)\rightleftharpoons 2H_2(g)+S_2(g)[/tex]
Initial conc. 0.097 M 0M 0M
At eqm. conc. (0.097-2x) M (2x) M (x) M
The expression for [tex]K_c[/tex] is written as:
[tex]K_c=\frac{[H_2]^2\times [S_2]}{[H_2S]^2}[/tex]
[tex]K_c=\frac{(2x)^2\times x}{(0.097-2x)^2}[/tex]
[tex]9.30\times 10^{-8}=\frac{(2x)^2\times x}{(0.097-2x)^2}[/tex]
[tex]x=0.00060[/tex]
Equilibrium concentration of [tex][H_2][/tex]= 2x= [tex]2\times 0.00060=0.0012M[/tex]
a. Describe the molecule chlorine dioxide, CIO in terms of three possible resonance structures.
b. Do any of these resonance structures satisfy the octet rule for every atom in the molecule? Why or why not?
Answer:
See explanation
Explanation:
The compound ClO2 has 19 valence electrons. ClO2 is a bent molecule with tetrahedral electron pair geometry but has two lone pairs of electrons. This is indicated by the presence of four electron pairs on the outermost shell of the central atom.
The molecule has an odd number of valence electrons, hence, it is generally regarded as a paramagnetic radical. None of the proposed Lewis structures for the molecule is satisfactory because none of them obeys the octet rule.
From the images attached, one can easily see that the electron dots around the oxygen and chlorine atoms does not satisfy the octet rule in all the resonance structures shown.
What specific portion of the gill is used to increase surface area though which gas (oxygen and carbon dioxide) exchange take place?
Answer:
gill lamellae
Explanation:
Gills in fishes are structures that permit fish to carry out gaseous exchange in water. Fishes exchange gases such as oxygen and carbon dioxide using gills.
Fish gills carry out their activity mainly through its major component called the gill lamellae. These are comb-like filaments which help increase the surface area of the gills in order to facilitate gaseous exchange
I Need Help Please ?
Answer:
Not sure dude goodluck
Explanation:
In carbon dioxide (CO2), there are two oxygen atoms for each carbon atom. Each oxygen atom forms a double bond with carbon, so the molecule is formed by two double bonds.
Two double bonds means that the total number of electrons being shared in the molecule is
Answer:
The Answer is eight.
Explanation:
Sorry if it's too late and it doesn't help! But I hope you have a magnificent day! :3
Answer:
8
Explanation:
I had this question on my quiz and got it right.
How many milliliters of 0.500 M HBr would be required to react with 40.0 mL of 0.300 M Ca(OH)2?
Answer:
48dm³
Explanation:
Given reaction:
Ca(OH)₂ + 2HBr → CaBr₂ + 2H₂O
Parameters:
Concentration of HBr = 0.5M
Volume of Ca(OH)₂ = 40mL
Concentration of Ca(OH)₂ = 0.3M
Solution:
To solve this problem, we are going to use the mole concept. We solve from the known specie to the unknown.
We first find the number of moles of the known specie which is the Ca(OH)₂ ;
number of moles = concentration x volume
number of moles = 0.3 x 40 x 10⁻³ = 0.012moles
From the reaction equation;
1 mole of Ca(OH)₂ requires 2 moles HBr
0.012 moles of Ca(OH)₂ will require 0.012 x 2 = 0.024moles of HBr
Now,
To find the volume of HBr;
Volume = [tex]\frac{number of moles }{concentration}[/tex]
Volume = [tex]\frac{0.024}{0.5}[/tex] = 0.048dm³
In mL;
Volume 0.048 x 1000 = 48dm³
Calculate the concentration of buffer components present in 210.00 mL of a buffer solution that contains 0.300 M NH4Cl and 0.300 M NH3 immediately after the addition of 1.00 mL of 6.00 M HNO3.
Answer:
[NH3] = 0.270M
[NH4Cl] = 0.327M
Explanation:
The HNO3 will react with the weak base, NH3, as follows:
HNO₃ + NH₃ → NH₄⁺ + NO₃⁻
Initial moles of each specie of the buffer:
NH3 = NH4⁺ 0.210L * (0.300mol/L) = 0.063moles
The moles added of HNO3 = Additional moles of NH4Cl and the moles substracted of NH3:
0.001L * (6mol / L) = 0.006 moles.
After the addition:
Moles NH3 = 0.063mol - 0.006mol = 0.057moles
Moles NH4Cl = 0.063mol + 0.006mol = 0.0069moles
And their concentrations are:
[NH3] = 0.057moles / 0.211L = 0.270M
[NH4Cl] = 0.069moles / 0.211L = 0.327M
Select the word that is incorrect in the paragraph and replace it with a word which makes the statement correct:
Group 2 elements have two valence electrons in their outer shell and are considered metals. In order to form an ion, a Group 2 element will
gain two electrons and form a cation.
Ions can be made by single element or covalently bonded group of elements. The covalently bonded group of elements is called polyatomic ions or polyatomic atoms. In order to form an ion, a Group 2 element will loose two electrons and form a cation.
What is Ions?Any species that contain charge whether it is positive charge or negative charge is called ions. The example of polyatomic ions are sulfate, phosphate, nitrate etc.
Cation is the species that loose electron and attain positive charge while anion is a species which gain electron and attains negative charge so when anion and cation combine in fixed ration the the overall charge of the molecule is zero that is molecule is neutral, the charge over cation and anion is also called oxidation state. In order to form an ion, a Group 2 element will loose two electrons and form a cation.
Therefore, in order to form an ion, a Group 2 element will
loose two electrons and form a cation.
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Which statements best describe half lives of radioactive isotopes
Answer:
The half-life varies depending on the isotope.
Half-lives range from fractions of a second to billions of years.
The half-life of a particular isotope is constant.
Explanation:
Make sure you add the options
The Earth can gain or lose matter. True False
Answer:
True
Explanation:
According to some calculations, the Earth is losing 50,000 metric tons of mass every single year, even though an extra 40,000 metric tons of space dust converge onto the Earth's gravity well, it's still losing weight.
Answer:
true
Explanation:
Entropy is a measure of
1.
accuracy
2.
precision
3.
the disorder of a system
4.
the attraction of a nucleus for an electron
Answer:
The answer is actually 3. The disorder of a system.
) What would be the effect on the molarity of the NaOH solution if some of the water evaporated from the Florence flask after the NaOH solution was standardized with the KHP
Answer:
The effect is the increasing of the molar concentration.
Explanation:
When you standarize a solution of NaOH with KHP you are establish its molar concentration (That is the amount of moles of NaOH per liter of solution).
If you evaporated some water of the solution, you are increasing its concentration because volume is decreasing doing the amount of moles per liter increasing.
A balloon contains 1.1 L of gas at a pressure of 0.80 atm. How will the volume
change if the pressure is increased to 2.0 atm?
Answer:
Final volume = 0.44 L
Explanation:
Given data:
Initial volume of balloon = 1.1 L
Initial pressure = 0.80 atm
Final volume = ?
Final pressure = 2.0 atm
Solution:
The given problem will be solved through the Boly's law,
"The volume of given amount of gas is inversely proportional to its pressure by keeping the temperature and number of moles constant"
Mathematical expression:
P₁V₁ = P₂V₂
P₁ = Initial pressure
V₁ = initial volume
P₂ = final pressure
V₂ = final volume
Now we will put the values in formula,
P₁V₁ = P₂V₂
0.80 atm × 1.1 L = 2.0 atm × V₂
V₂ = 0.88 atm. L/ 2.0 atm
V₂ = 0.44 L
Please help will give brainliest _________________________________________________________________________________________________________________________________________
Answer:
What subject is this for?
Explanation:
A block of lead weighs 11.3 grams. How many atoms of lead are in this sample?
• Use 6.022 x 1023 mol
for Avogadro's number.
Answer:
To get the number of atoms in this sample, we first need the number of moles of lead in 11.3 grams
Number of moles of Lead:
Molar mass of lead = 207 grams / mol
Number of moles = given mass / molar mass
Number of moles = 11.3 / 207
Number of moles = 0.05 moles
Number of atoms of lead in 11.3 gram sample:
Number of atoms = Number of moles * avogadro's number
Number of atoms = 0.05 * 6.022 * 10²³
Number of atoms = 5 * 10⁻² * 10²³ * 6.022
Number of atoms = 30.11 * 10²¹
11.3 g block of lead contains 3.29×10²² atoms
From Avogadro's hypothesis, we understood that 1 mole of any substance contains 6.022×10²³ atoms. Thus,
1 mole of lead = 6.022×10²³ atoms
Recall:
1 mole of lead = 207 g
Thus,
207 g of lead = 6.022×10²³ atomsWith the above information in mind, we can obtain the number of atoms in 11.3 g block of lead as illustrated below:
207 g of lead = 6.022×10²³ atoms
Therefore,
11.3 g of lead = (11.3 × 6.022×10²³) / 207
11.3 g of lead = 3.29×10²² atomsThus, 11.3 g block of lead contains 3.29×10²² atoms
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assuming the temperature is held constant, how could you increase the pressure inside a container by a factor of 3
The pressure can be increased by a factor of 3 by decreasing the volume by a factor of 3.
Ideal Gas Equation:Given that the temperature of the system is held constant. So it implies that it is an isothermal process.
Now we know that the ideal gas equation is given by:
PV = nRT
where, P is the pressure
V is the volume
n is the number of moles
R is the gas constant, and
T is the temperature
Assuming n is constant, R is universal as constant, so if T is also constant, then:
PV = constant
So if P becomes 3P. that is the pressure increased by a factor of 3, then V must become V/3, so that: (3P)(V/3) = PV = constant.
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what element has a higher ionization energy carbon or silicon
1. What 2 subatomic particles have charges? List the particle name and its charge.
Answer: Proton - positive charge (+)
Neutron - neutral charge (0)
Electron - negative charge (-)
Explanation:
Which set of procedures would be best to follow when separating a mixture of sand, salt, and water?
Answer:
Pour the mixture through a filter to separate the sand, then evaporate the liquid to separate the salt.
Explanation:
There are various methods used to separate single substances from a mixture. The method adopted depends upon the type of mixture and the ingredients used in it. According to the given question, the mixture comprises of sand, salt and water. Here, the first process will be the process of filtration. Through filtration, the salt-water solution and sand can be separated. Salt-water solution can be separated by the process of evaporation in which sat and water will be separated individually.
My made-up polyatomic ion goldate acts a lot like chlorate (it has the same charge and the same number of oxygens). What would the name be for the acid, HG004(aq)?
a. Hydrogen diogoldate
b. Goldous acid
c. Goldic acid
d. Pergoldic acid
e. None of these
Answer:
d. Pergoldic acid
Explanation:
chlorate = ClO₃⁻
Goldate GoO₃⁻
On this basis we can infer that HClO₄ and HGoO₄ will be similar .
HClO₄ is called perchloric acid , hence HGoO₄ will be called pergoldic acid.
2. Which gas is NOT an efficient greenhouse gas?
A. Helium
B. Methane
C. Carbon dioxide
D. Water vapor
Answer:
helium
Explanation:
remaining three are efficient gas
Among the options given below, helium is not an efficient greenhouse gas. Thus, the correct option for this question is A.
What do you mean by Greenhouse gases?Greenhouse gases are those gases that significantly allow solar radiation in order to enter but prevent the escape of heat radiations of longer wavelengths. The names of common greenhouse gases are carbon dioxide, methane, nitrous oxide, CFCs, etc.
According to the context of this question, the presence of these gases in the atmosphere is responsible for the phenomenon of keeping the earth warm. This is known as Greenhouse effect. These gases stimulate the phenomenon of global warming.
Therefore, among the options given below, helium is not an efficient greenhouse gas. Thus, the correct option for this question is A.
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Calculate the number of grams of CuSO4 found in 3.29 mL of a 4.00 M CuSO4 solution. ______ grams CuSO4
Answer:
0.0132 g CuSO₄
General Formulas and Concepts:
[tex]\text{Molarity}=\frac{\text{moles of solute}}{\text{liters of solution}}[/tex]
Explanation:
Step 1: Define variables
3.29 mL
4.00 M CuSO₄
x g CuSO₄
Step 2: Define conversions
1000 mL = 1 L
Step 3: Solve
Convert mL to L: [tex]\text{3.29 mL}(\frac{\text{1 L}}{\text{1000 mL}} )[/tex] = 0.00329 LSubstitute: [tex]\text{4.00 M} \ CuSO_4=\frac{\text{x g} \ CuSO_4}{\text{0.00329 L}}[/tex]Multiply both sides by L: [tex]\text{0.01316} \ CuSO_4=\text{x g} \ CuSO_4[/tex]Rewrite: [tex]x = 0.01316 \ g \ CuSO_4[/tex]Step 4: Simplify
We are given 3 sig figs.
0.01316 g CuSO₄ ≈ 0.0132 g CuSO₄
A sample of sodium bicarbonate is placed in an evacuated container at allowed to reach equilibrium. What will be the total pressure?
Complete Question
Sodium carbonate, Na2CO3(s), can be prepared by heating sodium bicarbonate, NaHCO3(s).
2NaHCO3(s) ------> Na2CO3(s) + CO2(g) + H2O(g) Kp = 0.23 at 100oC
If a sample of NaHCO3 is placed in an evacuated flask and allowed to achieve equilibrium at 100oC, what will the total gas pressure be?
Answer:
The value is [tex]P_T = 0.959 \ atm [/tex]
Explanation:
From the question we are told that
The equation is
[tex]2NaHCO_3_{(s)} \rightarrow Na_2CO_3_{(s)} + CO2_{(g)} + H2O_{(g)}[/tex]
Generally the equilibrium partial pressure is mathematically represented as
[tex]K_p = P_{CO_2} + P_{H_2O}[/tex]
Here
[tex] P_{CO_2} \ and \ P_{H_2O}[/tex] are partial pressures of [tex] CO_2 \ and \ H_2O [/tex] gases
Note: when writing the formula for equilibrium partial pressure we consider only the gas in the reaction
Let assume that
[tex]P_{CO_2} = a[/tex]
Generally [tex]P_{CO_2} = P_{H_2O}[/tex] since they are both products of the reaction
So
[tex]K_p = a^2 [/tex]
From the question we are told that [tex]K_p = 0.23 [/tex]
So
[tex] 0.23= a^2 [/tex]
=> [tex] a = \sqrt{0.23} [/tex]
=> [tex] a = \sqrt{0.23} [/tex]
=> [tex] a = 0.4796 \ atm [/tex]
So
[tex]P_{CO_2} = 0.4796 \ atm[/tex]
and
[tex]P_{H_2O} = 0.4796 \ atm [/tex]
So the total pressure is
[tex]P_T = 0.4796 + 0.4796[/tex]
=> [tex]P_T = 0.959 \ atm [/tex]
The numbers represent the change in energy for a chemical reaction. They are calculated by subtracting the energy of products from the energy of reactants. Which number would result from an endothermic reaction?
Answer:
800
Explanation:
took the test and got it right
The numbers represent the change in energy for a chemical reaction. They are calculated by subtracting the energy of products from the energy of reactants. 800 would result from an endothermic reaction.Therefore, the correct option is D.
What are the various types of reactions?
There are different types of reactions, such as the endothermic reaction, where the energy is used for the product's formation, and the exothermic reaction.
The energy is released in an exothermic reaction, resulting in a negative result, whereas the energy is used in an endothermic reaction, resulting in a positive result.
Any chemical reaction that absorbs heat from its surroundings is an endothermic reaction. The absorbed energy serves as the activation energy for the reaction to take place.
Thus, 800 would result from an endothermic reaction, the correct option is D.
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Your question is incomplete, most probably your question was
The numbers represent the change in energy for a chemical reaction. They are calculated by subtracting the energy of products from the energy of reactants. Which number would result from an endothermic reaction?
–212
0
-1
800
which two options are examples of chemical changes?
A. A shinny metal bar glows red and expands when heated.
B. white piece of paper turns black and gives off a smell when burned
C. When two clear colorless liquids are mixed together, a white solid forms
D. A white powder mixed with a clear, colorless liquid makes a solution that is also clear, colorless liquid
Answer:
B
Explanation:
It's the only thing that actually changes into something different and when u burn it it makes chemicals
The table below gives the numbers of protons, electrons, and neutrons in four atoms.
Number of neutrons
Number of protons
19
Number of electrons
9
Atom
1
12
3
collo
18
10
9
9
9
10
4
19
Based on the table, which atom has a charge of -12
O 1
O 2
03
4
Answer:
THE ANSWER IS D UR WELCOME.
Explanation:
How would you classify a creepy
crawly with no vertebrae and more
than 6 jointed legs?
Rileach
s. snake
T. spider
v.cockroach
Answer:
T
Explanation:
A Spider is a creepy crawly with no vertebrae and more than 6 jointed legs.
The Spider belongs to the class Arachnida . The Spider can be referred to as a non-vertebrates hence , they don't have a vertebrae(backbone).
The Spider and Cockroach are both non-vertebrates but with different pairs of legs. A cockroach is belongs to the class Insecta in which those under this class have only six jointed legs.
The Spider has eight jointed legs which is more than six and is a characteristic of Arachnids.
A snake on the other hand is a vertebrate which exempts it from being the answer.
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