Answer:
physical
Explanation:
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Please help me with this Chemistry problem..
Which of these is an example of a physical change?
à rusting metal
& browning fruit
burning wood
melting ice
Answer:
The correct answer is Water boiling. Examples of physical change are freezing of water, boiling of water, melting of wax, etc. Examples of chemical change are digestion of food, burning of paper, rusting of metal, silver tarnishing, etc.
Continental crust layer of blank which forms the blank
Help me to balance this equation please
Answer:
H202(aq)+2Fe2+(aq)+2H+=>2fe3+(aq)+2H20(l)
Explanation:
H202(aq)+2Fe2+(aq)+2H+=>2fe3+(aq)+2H20(l)
H202(aq)+2Fe2+(aq)+2H+=>2fe3+(aq)+2H20(l)
Which of the following statements about thermal energy is true? As you hold a cup of hot water, the heat moves to your hand. As you hold a cup of cold milk, your hand cools the milk. As you hold a cup of hot water your hands cool the water. As you hold a glass of cold milk, the cold travels to your hand.
Answer: As you hold cold milk.... travels to your hand
Explanation:
Cold and hot are compared to your own body temperature. So yeah that's kind of off topic but yeah. Anyways, to the explanation: so, this can be tested--obviously--by literally doing what the statement says. after you are done holding the milk, you will notice your hand is cold. This is because the milk is cooling down your hand to balance out the temperatures.
a buffer contains equal amounts of a weak acid and conjugate base and has a ph of 5.25. how will the concentration of conjugate base in the buffer change after the addition of a small amount of strong base?
The concentration of conjugate base in the buffer change after the addition of a small amount of strong base The concentration of conjugate base will increase. HA+BOH ⇒ H2O +AB
Buffer capacity refers to the amount of added acid or base that can be neutralized by a buffer. This is determined by the concentration of the conjugate acid and conjugate base. As these concentrations increase, the buffering capacity increases. A buffer is a solution that can withstand changes in pH due to the addition of acidic or basic components.
Can neutralize small amounts of added acids or bases and keep the pH of the solution relatively stable. When a strong base is added to a buffer the hydroxide ions are consumed by the weak acid, forming water, and consumed by the weak conjugate base of the acid. The number of weak acids decreases and the number of conjugate bases increases.
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3.4 x 10^23 atoms of potassium to grams
To solve this problem, we must take into account Avogadro's number. Avogadro's number tells us that in one mole of any substance there are 6.022x10^23 atoms. Applying this relationship we have that the moles of potassium (K) are:
[tex]\begin{gathered} molK=givenatomsK\times\frac{1molK}{6.022\times10^{23}atoms} \\ \end{gathered}[/tex][tex]\begin{gathered} molK=3.4\times10^{23}atomsK\times\frac{1molK}{6.022\times10^{23}atoms} \\ molK=0.6molK \end{gathered}[/tex]Now, to go from moles to grams, we must multiply the moles by the molar mass of potassium. The molar mass of potassium is 39.1g/mol. So, the grams of potassium will be:
[tex]gK=givenmolK\times\frac{MolarMass,gK}{1molK}[/tex][tex]\begin{gathered} gK=0.6molK\times\frac{39.1gK}{1molK} \\ gK=22.1gK \end{gathered}[/tex]Answer: In 3.4x10^23 atoms of potassium there are 22.1 grams
is the process of mixing ethanol and water exothermic or endothermic? how do you know (use numeric data to justify)? does this suggest presence of large clusters or small clusters in the mixture?
The reaction is exothermic as it involves a bond-forming process
when the liquids are mixed temperature of the reaction between the mixture increases.
There are small and large clusters in the mixture
The exothermic reaction involves the formation of new bonds which involves a combination of the bonds to form a new compound in our case water has hydroxy ions that bond with those of ethanol.
Mixing ethanol and water in volumetric glassware reduces the volume and increases the temperature.
The numerical example
Fill two 250 mL graduated cylinders to the line with water and ethanol pure temperature sensor shows both at room temperature. Next, move the temperature probe to an empty 500 mL graduated cylinder and pour the contents of the two smaller cylinders simultaneously and mix well.
The temperature of the mixture will rise by about 8 °C and the volume will decrease to 480 this indicates that the reaction is exothermic as the temperature rises and volume reduces
yes, clusters are present as ethanol falls between the spaces left by water as it has small molecules than that of water.
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You examined the effects of heat on equilibrium in part iv. Was the reaction you observed endo- or exo- thermic? does heat act as a reactant or product? what happened when you removed heat by placing the solution in the ice bath? what would you expect to happen if you were to add heat?.
1) The reaction is exothermic and heat is a product
2) The color would turn to pink.
What is an endothermic reaction?Let us recall that an endothermic reaction is one in which the increase in the temperature of the system would drive the forward reaction. This implies that the equilibrium would shift to the right when the set up is heated. Since the color of the solution changes to blue when heated hence the reaction is exothermic.
If you removed heat by placing the solution in the ice bath, we can see that we have removed the heat thus we expect that the reverse reaction would take place and the color would change to pink.
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a compound is found to contain 13.65 % carbon and 86.35 % fluorine by mass. what is the empirical formula for this compound? to answer the question, enter the elements in the order presented above.
Answer:
[tex]CF_{4}[/tex]
Explanation:
See attached worksheet
QUICK QUESTION...
What is the best method to use in extracting orange sugar from a whole orange
What is it you are making exactly? It is going to be for a recipe of some sort, like a beverage or food? If you could sort of expand on what the purpose is for, I think I may be able to help you find the best method for the extraction.
what statements are always true about limiting reactants? select one or more: there will be an excess of other reactants at the end of the reaction. the limiting reactant is completely used up in the reaction. the limiting reactant is always the same for a given reaction. the limiting reactant dictates the amount of product. the limiting reactant has a lower mass than other reactants.
There will be an excess of other reactants at the end of the reaction are always true about limiting reactants.
Why do reactants have a limiting effect?The reagent (compound or element) that must be completely consumed in a chemical reaction is known as the limiting reactant. Because there is no more reactant, limiting reactant is also what stops a reaction from continuing.
Limiting factors in stoichiometry are the reagents or reactants that are used by a chemical reaction before other reagents. The reactant or reagent having the lowest supply in relation to its required ratio compared to other reactants within the system is the limiting factor.
A chemical reactant known as a limiting reagent restricts the amount of product that may be produced. Based on the reagents (reactants) at hand, the limiting reagent produces the least amount of product. The theoretical yield refers to this minimum product yield.
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is CL3 a compound element or mixture
Answer:
Elements
Explanation:
I'll assume that the correct element symbol is Cl, not CL. CL would mean a compound made up of one carbon (C) and one Unknown element (L), Cl means chlorine.
I aslo wonder if the compound is [tex]Cl_{2}[/tex] and not [tex]Cl_{3}[/tex]. Regardless, both would be elements. A compound is made up of 2 or more different elements. A mixture is 2 or more compounds.
3.23x106 kJ to kcal
Express the value in kilogploring to three significant figures
help me please!
Hence 3.23×10⁶kJ = 771970 kilo calorie.
What is kilo joule?Kilo joule is a unit of energy that is equal to 1000 joules.
1 kilojoule is equal to 1000 joules:
∵ 1kJ = 0.239kcal
∴ 3.23×10⁶kJ = 3.23×10⁶ × 0.239
= 771970 kcal
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you need to prepare 1 l of the acetic acid/acetate buffer. you decided to mix 300 ml of 0.45 m acetic acid acid and 100 ml of 0.65 m naoh plus water to a final volume of one liter. the pka of acetic acid is 4.75. 1. calculate the ph of your buffer solution. 2. naoh is not the conjugate base to acetic acid. explain why you can use naoh to make an effective acetate buffer.
The pH of buffer solution is 4.72.
1) Molarity of acetic acid = 0.45 M
The volume of acetic acid = 300 ml
Molarity of NaOH = 0.65 M
Volume of NaOH = 100 ml
An acidic buffer solution is calculated by using Henderson's equation:
pH = pKa + ㏒[salt] / [acid]
where pKa = 4.75
pH = 4.75 + ㏒[0.065M] / [0.07M]
pH = 4.75 + ㏒(0.929)
pH = 4.75 - 0.03
pH = 4.72
Therefore, the pH of the buffer solution is 4.72.
2) NaOH is not the conjugate base to acetic acid. As we know NaOH is a strong base and acetic acid is a weak acid. Thus, an acid-base reaction occurs between acetic acid and NaOH, thus forming CH₃COONa, which is the conjugate base of acetic acid.
Acidic buffer solution is formed by mixing of weak acid and its conjugate salt of strong base. Thus, NaOH acts as limiting reactant and only CH₃COOH and CH₃COONa is present in solution. Thus, CH₃COOH is weak acid and CH₃COONa is its conjugate salt of strong base forms buffer solution. In the reaction of NaOH and CH₃COOH, NaOH gets completely reacted and forms CH₃COONa. Thus, NaOH is added to make an effective acetate buffer.
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A certain atom contains 53 protons, 78 neutrons, and 54 electrons. What is the mass number of this atom?.
The mass number of an atom that has 53 protons, 78 neutrons, and 54 electrons would be 131.
A mass number can be described as the sum total of the number of protons and neutrons that are contained within the nucleus of an atom.
If we want to calculate the mass number of an atom, we need to add the number of neutrons present inside the atoms with the number of protons present inside the atom.
As mentioned in the question, the number of protons inside the said atom is 53 whereas the number of neutrons is 78. Hence,
53+78= 131
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Why are low pressure systems associated with high temperatures?
Low pressure systems associated with high temperatures because warm air rises :)
Which of the following diagrams has correctly shaded the metals in blue?
1) Groups of elements in the periodic table.
Metals are located in the middle and left side of the periodic table.
The second picture has correctly shaded the metals.
.
Consider the hydrate calcium chloride dihydrate: cacl2 · 2h2o. how many hydrogen atoms are in the compound?
Consider the hydrate calcium chloride dihydrate hydrogen atoms are in the compound are four
Hydrate calcium chloride dihydrate is the excellent water soluble crystalline calcium sources used compatible with chloride and chloride compounds can conduct electricity when fused or dissolved in water and here given compound is CaCl₂ × 2H₂O
So in that compound the hydrogen atom are four because this compound or this equation is balanced so in that compound four hydrogen atom are present
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Answer:
4
Explanation:
2h2(g)+O2(g)----> 2H2O(g)
How any moles of o2 are required to react with 2 moles of H2
The number of moles of [tex]O_2[/tex] required to react with 2 moles of [tex]H_2[/tex] according to the reaction will be 4 moles.
Stoichiometric problemFrom the balanced equation of the reaction:
[tex]2H_2 (g) + O_2 (g) -- > 2H_2O (g)[/tex]
The mole ratio of hydrogen to oxygen is 2:1. This means that for every 1 mole of hydrogen that reacts to form 1 mole of water, 0.5 moles of oxygen is required. Also, for every 1 mole of oxygen, 2 moles of hydrogen are required.
Once the mole of hydrogen increases, the mole of oxygen also has to increase proportionately. Otherwise, oxygen becomes limited in availability, and hydrogen will be in excess.
From the equation of the reaction, 1 mole of oxygen requires 2 moles of hydrogen. Thus, with 2 moles of oxygen, 4 moles of hydrogen will be needed for a complete reaction.
In summary, the number of moles of [tex]O_2[/tex] that are required to react with 2 moles of [tex]H_2[/tex] is 4 moles.
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in the laboratory, a student adds 44.2 ml of water to 20.6 ml of a 0.652 m hydroiodic acid solution. what is the concentration of the diluted solution? assume the volumes are additive.
The concentration of diluted solution is 0.2 M.
The concentration and volume are related by the formula - [tex] M_{1}[/tex] [tex] V_{1}[/tex] = [tex] M_{2}[/tex] [tex] V_{2}[/tex], where [tex] M_{1}[/tex] and [tex] M_{2}[/tex] are initial and final concentration. [tex] V_{1}[/tex] and [tex] V_{2}[/tex] are initial and final volumes.
Keep the values in relation to find the concentration of final diluted solution.
0.652 × 20.6 = [tex] M_{2}[/tex] × (44.2 + 20.6)
Performing addition on Right Hand Side
0.652 × 20.6 = [tex] M_{2}[/tex] × 64.8
Performing multiplication and division
[tex] M_{2}[/tex] = 13.43÷64.8
[tex] M_{2}[/tex] = 0.2 M
Thus, the diluted solution is 0.2 M.
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Write the ionic equation
Ba(NO3)₂ (aq) + Na₂S04 (aq).
A particular compound has an enthalpy of vaporization of 28900 J/mol. At 278 K it has a vapor pressure of 103 mmHg. What is its vapor pressure at 309 K? (R = 8.31 J/(K· mol))a. 29.4mmhgb. 99.5mmhgc. 107mmhgd. 194mmhge. 361mmhg
Answer:
[tex]E\text{ : 361 mmHg}[/tex]Explanation:
Here, we want to get the vapour pressure of the compound at the given temperature
We can use the Clausius-Clapeyron equation for this
Mathematically, we have this as:
[tex]\ln (\frac{P_1}{P_2})\text{ = -}\frac{\Delta H}{R}(\frac{1}{T_1}-\frac{1}{T_2})[/tex]So,let us identify the values:
P1 = 103 mmHg
P2 = ?
ΔH = 28,900
R = 8.31
T1 = 278 K
T2 = 309 K
We now proceed to substitute these values into the equation above as follows:
[tex]\begin{gathered} \ln (\frac{103}{P_2})\text{ = -}\frac{28900}{8.31}(\frac{1}{278}-\frac{1}{309}) \\ \\ \ln (\frac{103}{P_2})\text{ = -3477.74 (}\frac{31}{85902}) \\ \\ \ln (\frac{103}{P_2})\text{ = -1.255} \\ \\ e^{-1.255}\text{ = }\frac{103}{P_2} \\ P_2\text{ = 361 mmHg} \end{gathered}[/tex]In two to three sentences, explain the importance of the following in a nuclear reactor:
control rods
containment structure
a moderator
The importance of the following below in a nuclear reactor are:
Control rods - Reaction maintenance.Containment structure - Protection for the environment.Moderator - slows electrons down.What is a Nuclear reactor?This is referred to as the device which is used to start up and control a fission or fusion nuclear chain reaction or nuclear fusion reactions.
The control rod is responsible for the absorption of neutrons so that the nuclear chain reaction taking place within the reactor core can be slowed or stopped. The containment structure help to prevent rays from getting into the environment thereby serving as a protective factor.
The moderator helps to slow down the speed of neutrons especially in those who have a very high speed thereby making it the correct choice.
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Which element has 2 valence electrons and 5 energy levels?
Answer:
its Boron i hope this helped.
Explanation:
The argon fluoride (arf) laser used in some refractive eye surgeries emits electromagnetic radiation of 193.3 nm wavelength. what is the frequency of the arf laser's radiation? what is the energy of a single quantum of the radiation?
The frequency of the radiation is 1.6 * 10^15 Hz while its energy is 1.056 * 10^-18 J
What is the frequency?Recall that the electromagnetic radiation is commonly called light. All the members of the electromagnetic spectrum are known to have the speed of light which is 3 * 10^8 m/s. The first task that we have is to obtain the frequency of the electromagnetic wave since we have the wavelength of the wave we seek.
Given that;
frequency = Speed of light/ wavelength
Frequency = 3 * 10^8 m/s/193.3 * 10^-9 m
Frequency = 1.6 * 10^15 Hz
Next we need to obtain the energy of the radiation and we have to do that from;
E = hf
E = energy of the photon
h = Planks constant
f = frequency of the photon
E = 6.6 * 10^-34 * 1.6 * 10^15 Hz
E = 1.056 * 10^-18 J
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Explain FULLY what this symbol means/can tell you ( be sure to talk about numbers of protons, neutrons, and electrons.
Chlorine has 17 protons, 17 electrons and 18 neutrons. The atomic number is 17 and the mass number is 35.
Explanations:The given element is Chlorine with an atomic number of 17 and a mass number of 35. The subscript serves as the atomic number while the superscript is the mass number.
The proton number is equal to the atomic number and electron number of a chlorine atom. Therefore;
Proton number = electron number = 17
For the neutron number
Neutron number is the difference between the mass number and the proton number;
Neutron number = Mass number - Proton number
Neutron number = 35 - 17 =18
Hence there are 18 neutron numbers in a chlorine atom
Carbon dioxide (co2) is a gaseous compound. calculate the percent composition of this compound. answer using one decimal place. what is the percent by mass of carbon? % what is the percent by mass of oxygen? %
The percent composition of carbon dioxide is as follows: 27.3% carbon, 72.7% oxygen.
To calculate the percent composition of the compound, we can assume that we have one mol of carbon dioxide. The molar mass of carbon dioxide is 44 g/mol.
Based on the molecular formula of carbon dioxide (CO₂), we can say that 1 mol of CO₂ contains 1 mol of carbon and two moles of oxygen.
The molar mass of carbon is 12 g/mol, and we can calculate its percent by mass by dividing the mass of carbon in carbon dioxide by the mass of carbon dioxide and multiplying the result by 100%:
%C = 100% * 12 g/mol / 44 g/mol
%C = 27.3%
Because carbon dioxide is made of only carbon and oxygen, we can the oxygen percent by mass by simply subtracting the carbon percent by mass from 100%:
%O = 100% - %C
%O = 100% - 27.3%
%O = 72.7%
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why we can't add an ion [ H+ ] to [ H3O+ ] ???
tysmmmm
The hydrogen ion, H⁺ cannot be added to a hydronium ion, H₃O⁺ , because the hydronium ion already contains a hydrogen ion.
What are the ions, H⁺ and H₃O⁺?The ions H⁺ and H₃O⁺ are the hydrogen ion and the hydronium ion respectively.
The hydrogen ion, H⁺ is formed when a hydrogen atom loses an electron. The hydrogen ion is known as a proton.
It is produced by acids when they dissociate in solution.
The hydronium ion, H₃O⁺ is formed when a water molecule combines with a hydrogen ion.
Because a hydrogen ion cannot exist on its own in aqueous solutions, the hydronium ion is the proper representation of the hydrogen ion in aqueous solutions.
Hence, the hydrogen ion H⁺, and the hydronium ion, H₃O⁺ are used interchangeably to represent acids in solution.
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what is a type of energy that powers a cell phone?