Answer:
Before adding the spatula tip amount: saturated solution.
After adding the spatula tip amount: super saturated solution.
Explanation:
A saturated solution is when the solute can dissolve in the solvent. For example, if you have an amount of water and you put calcium chloride into the water, and it dissolves, the solution is saturated.A supersaturated solution is when you put the calcium chloride into the solvent and the solute doesn't dissolve.So,Before adding the spatula tip amount: the solution is saturated.
After adding the spatula tip amount: the solution is super saturated.
Explanation:
When small amount of solute is added to a solvent and if it readily dissolves then this type of solution is known as an unsaturated solution.
For example, in the given situation when calcium chloride is first dissolved in water then it completely dissolves and this makes the solution unsaturated.
And, a saturated solution is defined as a solution which contains maximum amount of solute.
So, when a spatula tip full of calcium chloride is added into water then it is unable to dissolve the solute. This means the solution has become saturated.
Thus, we can conclude that solution before adding the spatula tip amount is unsaturated and after adding the spatula tip amount the solution becomes saturated.
How many valence electrons are in atom of radon?
Answer: 8
Explanation: Radon has 8 valence electrons. Radon is considered stable with a complete octet of electrons, filling the s and p orbitals.
three diagnostic characteristics of an acid are:
three diagnostic characteristics of a base are:
Answer:
Explanation:
An acid:
According to Arrhenius Theory, is a substance that interacts with water to produce excess hydrogen ion in an aqeous solution. The Bronsted -Lowry Theory defines an acid as a proton donor. The Lewis Theory states that an acid is an electron pair acceptor.A base:
Arrhenius defined a base as a substance which interacts with water to yield excess hydroxide ions in an aqeous solution. Bronsted-Lowry defined a base as a proton acceptor. The Lewis Theory described a base as an electron pair donor.Acids and bases have unique diagnostic characteristics that can be used to identify them. Acids taste sour, turn blue litmus paper red, and react with metals to produce hydrogen gas. Bases taste bitter, turn red litmus paper blue, and feel slippery.
Explanation:Three diagnostic characteristics of an acid:
An acid tastes sour.An acid turns blue litmus paper red.An acid reacts with metals to produce hydrogen gas.Three diagnostic characteristics of a base:
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What determines the types of chemical reactions that an atom participates in?
Answer:
The innermost electron shell of an atom can hold up to _____ electrons. ... What determines the types of chemical reactions that an atom participates in? the number of electrons in the outermost electron shell. Atoms with the same number of protons but with different electrical charges
The types of chemical reactions an atom can participate in are determined by its valence electrons, which are the outermost electrons in an atom. The atom's goal in a reaction is usually to achieve a stable structure, like a full or empty outer shell. The periodic table can also guide our understanding of an atom's reactive behaviour.
Explanation:The types of chemical reactions that an atom participates in are primarily determined by its electronic structure, specifically its valence electrons. These are the electrical charges contained in the outermost shell of an atom. Atoms generally strive to achieve a stable structure, which usually means filling up or emptying the outermost shell. Chemical reactions serve the purpose of reaching this stability. For instance, in a reaction between sodium (which wants to lose an electron) and chlorine (which wants to gain an electron) both atoms achieve a stable structure, forming sodium chloride, a common salt. Periodic table also provides useful information, as atoms in the same group (column) have similar chemical behaviours due to having the same number of valence electrons.
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• 1 mol of beryllium • 1 mol of salt • 1 mol of water • 1 mol of hydrogen Which statement is true about these substances?
Answer:
they all contain the same number of molecules at constant temperature and pressure
Answer:
Option D is correct! - They have different masses.
Explanation:
What are the two largest greenhouse gases
Carbon dioxide and M
ethane
What is the representative particle for an element?
Answer:
The representative particle for an element is AN ATOM.
Explanation:
Representative particle of a substance refers to the smallest unit of that substance, which can not be broken down into smaller particles. The representative particles of an element is an atom, because each element is made up of atoms, which are the smallest unit of that element; they can not be broken down further.
A representative particle is chemically identical with the parent element and will have all the properties of the parent element.
The representative particle for an element is typically the atom, for diatomic elements it's the molecule, and for ionic compounds, it is the formula unit. A mole of any substance contains 6.02 × 10²³ of these particles.
Explanation:The representative particle for an element is the smallest unit in which a substance naturally exists. For most elements, this is the atom, such as iron atoms, carbon atoms, and helium atoms. However, there are seven elements that exist naturally as diatomic molecules, namely H₂, N₂, O₂, F₂, Cl₂, Br₂, and I₂, making their representative particle the molecule. Molecular compounds like H₂O and CO₂ also exist as molecules, while ionic compounds such as NaCl and Ca(NO₃)₂ are represented by formula units. Each mole of a substance contains Avogadro's number (6.02 × 10²³) of representative particles, which is key when dealing with stoichiometry in chemistry.
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You are asked to make 43 grams of iron (Fe) from iron III oxide (Fe2O3) and carbon monoxide (CO) as shown in the chemical equation below.
Fe2O3 + 3CO → 2Fe + 3CO2
How many grams of iron III oxide must you use?
Question 10 options:
61.49 g
122.99 g
0.77 g
6863 g
To produce 43 grams of iron from the reaction Fe2O₃ + 3CO ightarrow 2Fe + 3CO₂, one would require approximately 61.48 grams of iron III oxide, following stoichiometry calculations based on molar masses and the balanced chemical equation.
To determine how many grams of iron III oxide (Fe₂O₃) are needed to make 43 grams of iron (Fe) using the reaction Fe₂O₃ + 3CO ightarrow 2Fe + 3CO₂, we will use the concept of stoichiometry. The molar mass of Fe is 55.85 grams per mole and the molar mass of Fe₂O₃ is approximately 159.69 grams per mole.
First, we need to determine the number of moles of iron that correspond to 43 grams:
Calculate moles of iron:
43 g Fe 1 mol Fe / 55.85 g Fe = 0.770 moles Fe.
Next, we use the stoichiometry of the reaction to find the moles of Fe₂O₃ needed. From the balanced equation, 1 mole of Fe₂O₃ produces 2 moles of Fe.
Calculate moles of Fe₂O₃:
0.770 moles Fe X (1 mol Fe2O3 / 2 mol Fe) = 0.385 moles Fe₂O₃.
Finally, convert the moles of Fe₂O₃ to grams:
0.385 moles Fe₂O₃ X 159.69 g Fe₂O₃/mol = 61.48 grams of Fe₂O₃ (rounded to two significant figures).
Therefore, to make 43 grams of iron, you must start with approximately 61.48 grams of iron III oxide.
Determine the internal energy change Δu of hydrogen, in kJ/kg, as it is heated from 500 to 700 K, using (a) the empirical specific heat equation as a function of temperature, (b) the value at the average temperature, and (c) the value at room temperature.
What caused the different pH values for the test solutions? Each solution has a different concentration of ions. hydroxide or hydrogen?
Answer: The correct answer is hydrogen.
Explanation:
pH is defined as the negative logarithm of hydrogen or hydronium ion concentration that are present in a solution.
The equation representing pH of the solution follows:
[tex]pH=-\log[H^+][/tex]
pH range of the solution varies from 0 to 14.
If the pH of the solution is from 0 to 6.9, the solution is said to be acidic.
If the pH of the solution is from 7.1 to 14, the solution is said to be basic.
If the pH of the solution is 7, the solution is said to be neutral.
Thus, different concentration of hydrogen ions will give us different values of pH.
Hence, the correct answer is hydrogen.
The different pH values for the test solutions result from the distinct concentrations of hydrogen (H+) or hydroxide (OH-) ions present in each solution. Acidic solutions have more H+ ions and a lower pH, while alkaline solutions have more OH- ions and a higher pH.
Explanation:The different pH values for the test solutions are caused by the varying concentrations of their hydrogen ions (H+) or hydroxide ions (OH-). The pH value is essentially a measure of the hydrogen ion concentration in the solution. Acidic solutions have a higher concentration of H+ ions and therefore a lower pH value (below 7), while basic or alkaline solutions have a higher concentration of hydroxide ions, resulting in pH values above 7. For instance, if one solution has more hydroxide ions than another, it will have a higher pH value, indicating it is more basic.
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When a glucose molecule loses a hydrogen atom as the result of an oxidation-reduction reaction, the molecule becomes _____.
A) hydrolyzed
B) oxidized
C) reduced
D) an oxidizing agent
Answer:
B) oxidized
Explanation:
When glucose loses a hydrogen atom, it is losing 1 proton and 1 electron. This loss of an electron means it is oxidized.
The glucose molecule becomes oxidized when it loses a hydrogen atom in an oxidation-reduction reaction. This reflects the loss of electrons, which is characteristic of oxidation, while gaining electrons, or hydrogen atoms, indicates reduction.(Option b)
Explanation:When a glucose molecule loses a hydrogen atom as the result of an oxidation-reduction reaction, the molecule becomes oxidized. This loss of hydrogen represents the molecule giving up electrons, which characterizes the process of oxidation. Conversely, when a molecule gains hydrogen atoms, it is said to be reduced.
In the context of glucose metabolism, an oxidizing agent would be a molecule like NAD+ or FAD, which accepts the electrons that are lost when glucose is oxidized. Hence, the carbohydrate is oxidized, liberating energy that the body can use.
Remember that in the process of cellular respiration, glucose is oxidized into carbon dioxide (CO2), and the oxygen is reduced while forming water (H2O). Glucose losing hydrogens means it is becoming oxidized, and the gaining of hydrogen by oxygen to form water indicates that oxygen is being reduced.
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What is the difference between the energy of spring A, stretched 0.6 meters, and spring B, stretched 0.3 meters, if they have the same spring constant? A. Spring A has more potential energy than spring B. B. Spring A has less potential energy than spring B. C. Springs A and B have the same potential energy. D. Springs A and B have the same kinetic energy.
Your answer would be A, Spring A has more potential energy.
Potential energy is exactly what it sounds like - energy that has the potential to exist due to stressors, but doesn't yet. In this case, the spring is ready to jump back into its original position however it can't because of it still being stretched, therefore this tension is what creates potential energy.
When you measure potential energy, the one with greater of it is the one where it has more stress being placed on it. In this case, spring A is being stretched furthest so it has the most potential energy.
Hope this helped!
Answer:
a
Explanation:
Match the following.
1. hybrid BB
2. dominant "pure breed" 3:1
3. recessive alleles Bb
4. phenotype ratio bb
Answer:
hybrid BB
Dominant Bb
recessive alleles bb
phenotype ratio 3:1
Answer:
hybrid BB
dominant Bb
recessive alleles bb
phenotype ratio 3:1
Explanation:
because phenotype ratio is a type of ratio so it match with the ratio. that's what l think
Chromium(III) oxide reacts with hydrogen sulphide gas to form chromium(III) sulphide and water. How many grams of hydrogen sulphide are required to produce 324.8 g of chromium(III) sulphide?
Answer:
165.726 g.
Explanation:
For the balanced equation:Cr₂O₃ + 3H₂S → Cr₂S₃ + 3H₂O,
It is clear that 1 mol of Cr₂O₃ and 3 mol of H₂S to produce 1 mol of Cr₂S₃ and 3 mol of H₂O.
Firstly, we need to calculate the no. of moles of 324.8 g of chromium(III) sulphide:no. of moles of Cr₂S₃ = mass/molar mass = (324.8 g)/(200.19 g/mol) = 1.62 mol.
Now, we can find the "no. of grams" of H₂S are needed:
Using cross multiplication:
3 mol of H₂S produces → 1 mol of Cr₂S₃, from stichiometry.
??? mol of H₂S produces → 1.62 mol of Cr₂S₃.
∴ The no. of moles of H₂S are needed = (3 mol)(1.62 mol)/(1 mol) = 4.86 mol.
∴ The "no. of grams" of H₂S are needed = (no. of moles of H₂S)(molar mass of H₂S) = (4.86 mol)(34.1 g/mol) = 165.726 g.
What is the theoretical yield of carbon dioxide?
a)0.993 g
b)2.98 g
c)3.65 g
d)8.93 g
Answer:
Hey how are you all doing the answer is 8.93 g
Explanation:
The theoretical yield of carbon dioxide is 8.93 g
Before performing chemical reactions, it is helpful to know how much product will be produced with given quantities of reactants. This is known as the theoretical yield. This is a strategy to use when calculating the theoretical yield of a chemical reaction. The same strategy can be applied to determine the amount of each reagent needed to produce a desired amount of product.
Carbon dioxide (CO2) became the first gas that was distinguished from ordinary air. In 1630 or so, Jan Baptist van Helmont, a Flemish chemist, identified a vapor distinct from the air when he burned charcoal in a closed vessel. He then called the vapor “wood gas” (spiritus sylvestris). He thought that it was an element or a single substance.1 In 1756, Joseph Black, a Scottish physician, noticed this gas when heating calcium carbonate (CaCO3). He called it “fixed air”. He also identified it from exhaled breath and described it as denser than the air faintly acidic. In 1803, John Dalton (an English chemist) proposed that this substance is comprised of one carbon atom and two oxygen atoms. Now, it is called “carbon dioxide”.Carbon dioxide is a chemical compound made up of a carbon atom and two oxygen atoms. Each of the oxygen atoms is attached to the central carbon atom by a double covalent bond. The C-O bond has a length of 116.3 pm. The configuration of the compound is linear and centrosymmetric. Its chemical formula is CO2.Learn more about Carbon dioxide
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An atom of lithium-7 has an equal number of(1) electrons and neutrons(2) electrons and protons(3) positrons and neutrons(4) positrons and protons
Answer: Electrons and protons
An atom of lithium-7 has an equal number of electrons and protons. Therefore, the correct option is option 2.
What is lithium?Lithium is a chemical substance with the atomic number three as well as the symbol Li. The material is a delicate alkali metal in white-silver. Under normal conditions, it is both the lowest population metal and the least populated inorganic element. Because lithium is an extremely reactive as well as flammable alkali metal, it must be stored in a vacuum.
When cut, it has a glossy luster, but wet air quickly corrodes it, turning it into an olive drab silvery gray, eventually merely a black patina. Only compounds, particularly pegmatitic minerals, which has also historically been the primary source of lithium, may exist naturally. An atom of lithium-7 has an equal number of electrons and protons.
Therefore, the correct option is option 2.
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The pictured compound has which of the following bonds?
Answer: There are C - C bonds and C - H bonds.
trust me! I took a test with this question and got 100! :)
The pictured compound has C - C bonds and C - H bonds.
What is a Bond?
This is defined as an attraction between atoms, ions or molecules which results in the formation of chemical compounds.
The compound is an alkane as the formula is C₄H₁₀(butane) which has only C - C bonds and C - H bonds single bonds thereby making option C the most appropriate choice.
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What is the total reduction potential of a cell in which lithium (li) is reduced and mercury (hg) is oxidized?
Answer: The total reduction potential of the cell is -3.89 V.
Explanation:
We are given:
Reduction of lithium follows the reaction:[tex]Li^++e^-\rightarrow Li[/tex]
The standard reduction potential for this is -3.04 V
Oxidation of mercury follows the reaction:[tex]Hg\rightarrow Hg^{2+}+2e^-[/tex]
The standard reduction potential for this is -0.85 V
The cell formed by these half reactions is: [tex]Hg/Hg^{2+}||Li^+/Li[/tex]
The cell potential, [tex]E^o_{cell}=E^o_{oxidation}+E^o_{reduction}[/tex]
[tex]E^o_{cell}=[-0.85+(-3.04)]=-3.89V[/tex]
Hence, the total reduction potential of the cell is -3.89 V.
How do polar molecules respond when they are placed between two metal plates one positively charged and one negatively charged ? A the molecules online and the electric field be the molecules joined together form in one large molecule see the molecules break apart as atoms migrate to the two plates d the molecule spin in circles
Answer:
The molecules align with the electric field
Explanation:
Polar molecules have dipoles (parts of the molecules have partial charges). This is because the atoms with a larger atomic mass attract more of the electron cloud of the molecule hence become partially electronegative. The other part of the molecule becomes partially positive. Therefore these parts of the molecule will align with opposite charges including in this case based on the charged metal plates. The positive dipole will align with the negative plate while the negative dipoles will align with the positive plate.
Answer:
The molecules align to the electric field.
Explanation:
A polar molecule is one that is neutral, that is, it does not have a net charge. But it has an internal distribution of charges that form a partially positive region and a partially negative region.
Coulomb's law indicates that charged bodies suffer a force of attraction or repulsion when approaching. The value of this force is proportional to the product of the value of its loads. The force is of attraction if the charges are of opposite sign and of repulsion if they are of the same sign. The force is inversely proportional to the square of the distance that separates them.
Then, following Coulomb's Law, the negatively charged end of the polar molecule will be attracted to the positively charged metal plate. And the positively charged end of the polar molecule is attracted to the negatively charged metal plate.
Then, the molecules align to the electric field.
Which is the noble gas notation for chlorine?
Answer:
[Ne] 3s² 3p⁵Explanation:
Chlorine's atomic number is 17.
That means that it has 17 protons and 17 electrons.
Then, you have to write the electron configuration for the 17 electrons.
The noble gas notation is a short notation that uses the previous noble gas symbol (closed in brackets) and adds the new electrons, filling the orbitals in increasing order of energy, which you can remember using Aufbau rules.
Then:
number of electrons: 17Previous noble gas: neon, which has 10 electrons.Then, you use [Ne] and add 17 - 10 = 7 more electrons.Since, the electron configuration of neon is 1 s² 2s² 2p⁶, the seven electrons that you have to add will occupy the orbitals 3s and 3p.Result: [Ne] 3s² 3p⁵ ← answer
Diversification is most effective when security returns are _________.
Answer:
negatively correlated
Interpolate: Use the equation to determine what the student enrollment in 2003 likely was.
students
Answer:
1244 students
Explanation:
That would be y = 82*3 + 998
= 1244.
Answer:
The expected student enrollment in 2003 is 1244.
Explanation:
The given diagram it is clear that the graph represents the relationship x and y, where x is number of years since 2000 and y is number of student enrollment.
From the given figure it is clear that the equation of best fit line is
[tex]y=82x+998[/tex] .... (1)
We need to find the expected student enrollment in 2003.
Year 2003 is 3 years since 2000.
Substitute x=3 in equation (1) to find the expected student enrollment in 2003.
[tex]y=82(3)+998[/tex]
[tex]y=246+998[/tex]
[tex]y=1244[/tex]
Therefore the expected student enrollment in 2003 is 1244.
How does water vapor get into the atmosphere?
Answer:
through the water cycle
Explanation:
Which would have a higher pH, a 0.1 M solution of a strong acid, or a weak acid? Why?
Answer:
0.1 M weak acid
Explanation:
The term pH simply means power of hydrogen which is basically a log (the exponent to base 10 of the concentration) of the concentration of the hydrogen ions.
Weak acids have a higher pH since their hydrogen concentration is lower than that of strong acids.
How much carbon dioxide can a single tree absorb in its lifetime?
Answer:
a tree absorb as much as 48 pound of carbon dioxide per year and can sequester 1 ton of carbon dioxide by the time it reaches 40 years old
When salt is dissolved in water, what happens to the water
Answer:
When salt is dissolved in water, many physical properties change, among them the so called colligative properties:
The vapor pressure of water decreases,The boiling point increases,The freezing point decreases, andOsmotic pressure appears.Explanation:
Colligative properties are the physical properties of the solvents whose change is determined by the number of particles (moles or ions) of the solute added.
The colligative properties are: vapor pressure, boiling point, freezing point, and osmotic pressure.
Vapor pressure:
The vapor pressure is the pressure exerted by the vapor of a lquid over its surface, in a closed vessel.
The vapor pressure increases when a solute is added, because the presence of the solute causes less solvent molecules to be near the surface ready to escape to the vapor phase, which means that the vapor pressure is lower.
Boiling point:
The boiling point is the temperature at which the vapor pressure of the liquid equals the atmospheric pressure. Since we have seen that the vapor pressure of water decreases when a solute occupies part of the surface, now more temperature will be required for the water molecules reach the atmospheric pressure. So, the boiling point increases when salt is dissolved in water.
Freezing point:
The freezing point is the temperarute at which the vapor pressure of the liquid and the solid are equal. Since, the vapor pressure of water with salt is lower than that of the pure water, the vapor pressure of the liquid and solid with salt will be equal at a lower temperature. Hence, the freezing point is lower (decreases).
Osmotic pressure:
Osmotic pressure is the additional pressure that must be exerted over a solution to make that the vapor pressure of the solvent in the solution equals the vapor pressure of the pure solvent. This additional pressure is proportional to the concentration of the solute: the higher the salt concentration the higher the osmotic pressure.
What is the number of moles of beryllium atoms in 36 g of be? 0.25 mol 4.0 mol 45.0 mol 320 mol?
Answer:
[tex]\boxed{\text {4.0 mol}}[/tex]
Explanation:
1 mol of Be = 9.012 g
[tex]\text{Moles of Be} = \text{36 g Be} \times \dfrac{\text{1 mol Be}}{\text{9.012 g Be}} = \text{4.0 mol Be}\\\\\text{There are }\boxed{\textbf{4.0 mol Be}} \text{ in 36 g of Be}[/tex]
Answer: Option (b) is the correct answer.
Explanation:
It is known that number of moles of a substance is equal to the given mass of the substance divided by its molar mass.
Mathematically, Number of moles = [tex]\frac{mass}{/text{\molar mass}}[/tex]
Molar mass of beryllium is 9 g/mol. Hence, putting the given values into the above formula as follows.
Number of moles = [tex]\frac{mass}{/text{\molar mass}}[/tex]
= [tex]\frac{36}{9 g/mol}[/tex]
= 4 moles
Thus, we can conclude that the number of moles present in 36 grams of Be are 4 moles.
When you perform this reaction, what substances could remain at the end of the reaction? Check all that apply.
excess reactant aqueous copper chloride
excess reactant aluminum
oxygen
product solid copper
carbon dioxide
product aqueous aluminum chloride
water
Answer:
a.) excess reactant aqueous copper chloride.
b.) excess reactant aluminum.
d.) product solid copper.
f.) product aqueous aluminum chloride.
g.) water.
Explanation:
just did the lab, here's the answers :)
Excess reactant aluminum, oxygen, product solid copper, product aqueous aluminum chloride, water could remain at the end of the reaction.
Explanation:
When performing the reaction between aluminum and copper chloride, there are several substances that could remain at the end of the reaction:
Excess reactant aluminum: If aluminum is present in excess, then it would remain at the end of the reaction.
Oxygen: If oxygen is introduced into the reaction, it could remain as a result of incomplete combustion.
Product solid copper: Copper is formed as a product of the reaction between aluminum and copper chloride.
Product aqueous aluminum chloride: Aluminum chloride is also formed as a product of the reaction.
Water: Water can also be present as a product depending on the conditions of the reaction.
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Malia was able to make a paper clip float on the surface of water what will most likely happen to the paper clip if a drop of dishwashing detergent is added near it
Deuterium is an isotope of hydrogen. The nucleus of a deuterium atom consists of one proton and one neutron. When two deuterium nuclei fuse, helium-3 is formed, and a neutron is emitted. Give the equation that illustrates this process?
Answer:
[tex]^2_1H+^2_1H->^3_2He+^1_0n[/tex]Explanation:
Remember that the atomic number of an element is the number of protons and the mass number is the number of protons plus neutrons.
1) Deuterium representation:
Hydrogen: ⇒ HOne proton: ⇒ [tex]_1H[/tex]One neutron: ⇒ add 1 to the mass number = 1 + 1 = 2 ⇒ [tex]^2_1H[/tex]2) Helium-3 representation:
He atom with 1 neutron: ⇒ mass number = 2 + 1 ⇒ [tex]^3_He[/tex]3) Neutron representation
Atomic number 0 and mass number 1: ⇒ [tex]^1_0n[/tex]4) Nuclear equation:
[tex]^2_1H+^2_1H->^3_2He+^1_0n[/tex] ← answerAnswer:
the answer is D. on edg 2020
Explanation:
An acidified solution was electrolyzed using copper electrodes. A constant current of 1.18 A caused the anode to lose 0.584 g after 1.52 ✕ 103 s. (a) What is the gas produced at the cathode and what is its volume at STP? name of gas volume of gas WebAssign will check your answer for the correct number of significant figures. L (b) Given that the charge of an electron is 1.6022 ✕ 10−19 C, calculate Avogadro's number. Assume that copper is oxidized to Cu2+ ions.
Answer:
[tex]\boxed{\text{(a) 209 mL; (b) } 6.09 \times 10^{23}}[/tex]
Explanation:
(a) Gas produced at cathode.
(i). Identity
The only species known to be present are Cu, H⁺, and H₂O.
Only the H⁺ and H₂O can be reduced.
The corresponding reduction half reactions are:
(1) 2H₂O + 2e⁻ ⇌ H₂ + 2OH⁻; E° = -0.8277 V
(2) 2H⁺ +2e⁻ ⇌ H₂; E° = 0.0000 V
Two important points to remember when using a table of standard reduction potentials:
The higher up a species is on the right-hand side, the more readily it will lose electrons (be oxidized). The lower down a species is on the left-hand side, the more readily it will accept electrons (be reduced}.H⁺ is below H₂O, so H⁺ is reduced to H₂.
The cathode reaction is 2H⁺ +2e⁻ ⇌ H₂, and the gas produced at the cathode is hydrogen.
(ii) Volume
a. Anode reaction
The only species that can be oxidized are Cu and H₂O.
The corresponding half reactions are:
(3) Cu²⁺ + 2e⁻ ⇌ Cu; E° = 0.3419 V
(4) O₂ + 4H⁺ + 4e⁻ ⇌ 2H₂O E° = 1.229 V
Cu is above H₂O, so Cu is more easily oxidized.
The anode reaction is Cu ⇌ Cu²⁺ + 2e⁻.
b. Overall reaction:
Cu ⇌ Cu²⁺ + 2e⁻
2H⁺ +2e⁻ ⇌ H₂
Cu + 2H⁺ ⇌ Cu²⁺ + H₂
c. Moles of Cu lost
[tex]n_{\text{Cu}} = \text{0.584 g } \times \dfrac{\text{1 mol}}{\text{63.55 g}} = 9.190 \times 10^{-3}\text{ mol Cu}[/tex]
d. Moles of H₂ formed
[tex]n_{\text{H}_{2}}} = 9.190 \times 10^{-3}\text{ mol Cu} \times \dfrac{\text{1 mol H}_{2}}{\text{1 mol Cu}} =9.190 \times 10^{-3}\text{ mol H}_{2}[/tex]
e. Volume of H₂ formed
Volume of 1 mol at STP (0 °C and 1 bar) = 22.71 mL
[tex]V = 9.190 \times 10^{-3}\text{ mol}\times \dfrac{\text{22.71 L}}{\text{1 mol}} = \text{0.209 L} = \boxed{\textbf{209 mL}}[/tex]
(b) Avogadro's number
(i) Moles of electrons transferred
[tex]\text{Moles of electrons} = 9.190 \times 10^{-3}\text{ mol Cu}\times \dfrac{\text{2 mol electrons}}{\text{1 mol Cu}}\\\\\\= \text{0.018 38 mol electrons}[/tex]
(ii) Number of coulombs
Q = It
Q = \text{1.18 C/s} \times 1.52 \times 10^{3} \text{ s} = 1794 C
(iii). Number of electrons
[tex]n = \text{ 1794 C} \times \dfrac{\text{1 electron}}{1.6022 \times 10^{-19} \text{ C}} = 1.119 \times 10^{22} \text{ electrons}[/tex]
(iv) Avogadro's number
[tex]N_{\text{A}} = \dfrac{1.119 \times 10^{22} \text{ electrons}}{\text{0.018 38 mol}} = \boxed{6.09 \times 10^{23} \textbf{ electrons/mol}}[/tex]