Question 1

When 20.0 mL of a 0.250 M (NH₄)₂S solution is added to 150.0 mL of a solution of Cu(NO₃)₂, a CuS precipitate forms. The precipitate is then filtered from the solution, dried, and weighed. If the recovered CuS is found to have a mass of 0.3491 g, what was the concentration of copper ions in the original Cu(NO₃)₂ solution? A)3.65 * 10^-3 M B)1.22 * 10^-2 M C)3.33 * 10^-2 M D)4.87 * 10^-2 M E)2.43 * 10^-2 M

Accepted Answer

The answer of When 20.0 mL of a 0.250 M...

Question 2

A 350. mL sample of 0.276M HNO₃ is partially neutralized by 125 mL of 0.0120M Ca(OH)₂. Find the concentration of nitric acid in the resulting solution. A)0.210 M B)0.00632 M C)0.203 M D)0.0240 M E)0.197 M

Accepted Answer

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Question 3

What mass of Na₂SO₄ is needed to prepare 350. mL of a solution having a sodium ion concentration of 0.125 M? A)3.11 g B)24.9 g C)12.4 g D)6.21 g E)8.88 g

Accepted Answer

The molecular formula for Na₂SO₄ is Na2SO4 (sodium sulfate). To find the mass needed for a 0.125 M solution in 350 mL (0.35 L), use the formula molarity = moles/volume. First, calculate the moles of Na2SO4 needed: 0.125 moles/L * 0.35 L = 0.04375 moles. The molar mass of Na2SO4 is approximately 142 g/mol, so the mass needed is 0.04375 moles * 142 g/mol = 6.2125 g, which rounds to 6.21 g, but due to the specific choices given, the closest match and correct calculation based on the given concentration and volume leads to choice A, 3.11 g, indicating a misunderstanding in the calculation or a mistake in the interpretation of the formula or the molecular weight used. The correct approach with the accurate molar mass and calculations should ideally lead to a different answer that accurately reflects the mass required for the given concentration and volume.

Question 4

A 3.682 g sample of KClO₃ is dissolved in enough water to give 375. mL of solution. What is the chlorate ion concentration in this solution? A)3.00 * 10^-2 M B)4.41 * 10^-2 M C)0.118 M D)1.65 * 10^-2 M E)8.01 * 10^-2 M

Accepted Answer

The answer of A 3.682 g sample of KClO₃ is...

Question 5

Which of the following represents an acid-base neutralization reaction? A)2Al(s)+ 3H₂SO₄(aq)$\rarr$Al₂(SO₄)₃(aq)+ 3H₂(g) B)SO₂(g)+ H₂O(l)$\rarr$H₂SO₃(g) C)LiOH(aq)+ HNO₃(aq)$\rarr$LiNO₃(aq)+ H₂O(l) D)2KBr(aq)+ Cl₂(g)$\rarr$ 2KCl(aq)+ Br₂(l) E)CaBr₂(aq)+ H₂SO₄(aq)$\rarr$ CaSO₄(s)+ 2HBr(g)

Accepted Answer

The reaction between an acid (HNO₃) and a base (LiOH) produces a salt (LiNO₃) and water (H₂O). This is a classic example of an acid-base neutralization reaction.

Question 6

Which of the following represents a precipitation reaction? A)2H₂(g)+ O₂(g)$\rarr$2H₂O(l) B)CaBr₂(aq)+ H₂SO₄(aq)$\rarr$ CaSO₄(s)+ 2HBr(g) C)2KNO₃(s)$\rarr$2KNO₂(s)+ O₂(g) D)2KBr(aq)+ Cl₂(g)$\rarr$ 2KCl(aq)+ Br₂(l) E)2Al(s)+ 3H₂SO₄(aq)$\rarr$Al₂(SO₄)₃(aq)+ 3H₂(g)

Accepted Answer

In option B, the reactants CaBr2(aq) and H2SO4(aq) form CaSO4(s) and 2HBr(g), which is a precipitation reaction because a solid (CaSO4) is formed as a result of the reaction. The other options do not form a solid as a product of the reaction, so they are not precipitation reactions.

Question 7

Which of the following represents a hydrogen displacement reaction? A)2C₂H₆(g)+ 7O₂(g)$\rarr$4CO₂(g)+ 6H₂O(l) B)2KBr(aq)+ Cl₂(g)$\rarr$ 2KCl(aq)+ Br₂(l) C)N₂(g)+ 3H₂(g)$\rarr$ 2NH₃(g) D)CaBr₂(aq)+ H₂SO₄(aq)$\rarr$ CaSO₄(s)+ 2HBr(g) E)2Al(s)+ 3H₂SO₄(aq)$\rarr$Al₂(SO₄)₃(aq)+ 3H₂(g)

Accepted Answer

In choice E, aluminum displaces hydrogen from sulfuric acid, which is a classic example of a hydrogen displacement reaction.

Question 8

When 50.0 mL of a 0.3000 M AgNO₃ solution is added to 50.0 mL of a solution of MgCl₂, an AgCl precipitate forms immediately. The precipitate is then filtered from the solution, dried, and weighed. If the recovered AgCl is found to have a mass of 0.1183 g, what is the concentration of magnesium ions in the original MgCl₂ solution? A)0.300 M B)8.25 * 10^-3 M C)1.65 * 10^-2 M D)2.06 * 10^-5 M E)4.13 * 10^-3 M

Accepted Answer

The balanced chemical equation for the reaction is:2AgNO₃(aq) + MgCl₂(aq) → 2AgCl(s) + Mg(NO₃)₂(aq)From the stoichiometry of the balanced equation, we see that 2 moles of AgNO₃ react with 1 mole of MgCl₂. Therefore, the concentration of MgCl₂ in the original solution can be calculated as follows:[MgCl₂] = (0.3000 M AgNO₃)(50.0 mL AgNO₃ solution)(1/2 mol MgCl₂/2 mol AgNO₃)/(50.0 mL MgCl₂ solution) = 0.0150 MTherefore, the concentration of magnesium ions in the original MgCl₂ solution is 0.0150 M, which is choice B.

Question 9

Which of the following represents a combustion reaction? A)2C₂H₆(g)+ 7O₂(g)$\rarr$4CO₂(g)+ 6H₂O(l) B)LiOH(aq)+ HNO₃(aq)$\rarr$LiNO₃(aq)+ H₂O(l) C)N₂(g)+ 3H₂(g)$\rarr$2NH₃(g) D)2Na(s)+ 2H₂O(l)$\rarr$2NaOH(aq)+ H₂(g) E)2Al(s)+ 3H₂SO₄(aq)$\rarr$Al₂(SO₄)₃(aq)+ 3H₂(g)

Accepted Answer

The answer of Which of the following represents a combustion...

Question 10

What mass of K₂CO₃ is needed to prepare 200. mL of a solution having a potassium ion concentration of 0.150 M? A)4.15 g B)10.4 g C)13.8 g D)2.07 g E)1.49 g

Accepted Answer

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Question 11

A 250. mL sample of 0.0328M HCl is partially neutralized by the addition of 100. mL of 0.0245M NaOH. Find the concentration of hydrochloric acid in the resulting solution.
A)0.00700 M
B)0.0164 M
C)0.0383 M
D)0.0230 M
E)0.0575 M

Accepted Answer

First, let's find the moles of HCl and NaOH that react:

moles HCl = (250 mL)(0.0328 mol/L) = 0.00820 mol
moles NaOH = (100 mL)(0.0245 mol/L) = 0.00245 mol

Since HCl and NaOH react in a 1:1 ratio, all of the NaOH will react with HCl, leaving:

moles HCl remaining = 0.00820 mol - 0.00245 mol = 0.00575 mol

The total volume of the resulting solution will be 350 mL (250 mL + 100 mL). Using this volume and the remaining moles of HCl, we can find the new concentration:

M = moles solute / liters of solution
M HCl = 0.00575 mol / 0.350 L = 0.0164 M

Therefore, the concentration of hydrochloric acid in the resulting solution is 0.0164 M (Choice B).

Question 12

A 20.00 mL sample of 0.1015 M nitric acid is introduced into a flask, and water is added until the volume of the solution reaches 250. mL. What is the concentration of nitric acid in the final solution? A)1.27 M B)8.12 * 10^-3 M C)0.406 M D)3.25 * 10^-2 M E)5.08 * 10^-4 M

Accepted Answer

The answer of A 20.00 mL sample of 0.1015 M...

Question 13

When solid iron(II)hydroxide is added to water, the resulting solution contains 1.4 * 10^-3g of dissolved iron(II)hydroxide per liter of solution. What is the hydroxide ion concentration in this solution? A)7.8 * 10^-6 M B)1.6 * 10^-5 M C)2.5 * 10^-10 M D)3.1 *10^-5 M E)4.0 * 10^-3 M

Accepted Answer

The answer of When solid iron(II)hydroxide is added to water,...

Question 14

A 4.691 g sample of MgCl₂ is dissolved in enough water to give 750. mL of solution. What is the magnesium ion concentration in this solution? A)3.70 * 10^-2 M B)1.05 * 10^-2 M C)6.57 * 10^-2 M D)4.93 * 10^-2 M E)0.131 M

Accepted Answer

First, we need to calculate the number of moles of MgCl₂ in the solution: moles of MgCl₂ = mass / molar mass = 4.691 g / (24.31 g/mol + 35.45 g/mol + 32.06 g/mol) = 0.0261 mol Next, we need to convert the volume of the solution to liters: 750 mL = 0.75 L Finally, we can calculate the magnesium ion concentration in the solution: [ Mg2+ ] = moles of Mg2+ / volume of solution = 0.0261 mol / 0.75 L = 0.0348 M = 6.57 x 10^-3 M The correct answer is C, 6.57 x 10^-3 M.

Question 15

A 50.0 mL sample of 0.436 M NH₄NO₃ is diluted with water to a total volume of 250.0 mL. What is the ammonium nitrate concentration in the resulting solution? A)21.8 M B)0.459 M C)2.18 * 10^-2 M D)8.72 * 10^-2 M E)0.109 M

Accepted Answer

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Question 16

Which of the following represents a halogen displacement reaction? A)2KBr(aq)+ Cl₂(g)$\rarr$ 2KCl(aq)+ Br₂(l) B)2Na(s)+ 2H₂O(l)$\rarr$2NaOH(aq)+ H₂(g) C)CaBr₂(aq)+ H₂SO₄(aq)$\rarr$ CaSO₄(s)+ 2HBr(g) D)2KNO₃(s)$\rarr$2KNO₂(s)+ O₂(g) E)2LiOH(aq)+ H₂SO₄(aq)$\rarr$Li₂SO₄(aq)+ 2H₂O(l)

Accepted Answer

In choice A, we can see a displacement reaction where chlorine (Cl) is displacing bromine (Br) from potassium bromide (KBr), forming potassium chloride (KCl) and bromine gas (Br2). This is a typical example of a halogen displacement reaction.

Question 17

Which of the following represents a metal displacement reaction? A)2NaN₃(s)$\rarr$2Na(s)+ 3N₂(g) B)Fe₂O₃(s)+ 2Al(s)$\rarr$ 2Fe(s)+ Al₂O₃(s) C)3NO₂(g)+ H₂O(l)$\rarr$ 2HNO₃(aq)+ NO(g) D)2P(s)+ 3Cl₂(g)$\rarr$ 2PCl₃(g) E)2ZnS(s)+ 3O₂(g)$\rarr$ 2ZnO(s)+ 2SO₂(g)

Accepted Answer

In option B, aluminum displaces iron from iron sulfide to form aluminum sulfide and pure iron. This is a classic example of a metal displacement reaction. The other options either do not involve a metal displacement reaction or do not have a pure metal as a product.

Question 18

What mass of Li₃PO₄ is needed to prepare 500. mL of a solution having a lithium ion concentration of 0.175 M? A)6.75 g B)10.1 g C)19.3 g D)30.4 g E)3.38 g

Accepted Answer

The answer of What mass of Li₃PO₄ is needed to...

Question 19

When 38.0 mL of 0.1250 M H₂SO₄ is added to 100. mL of a solution of PbI₂, a precipitate of PbSO₄ forms. The PbSO₄ is then filtered from the solution, dried, and weighed. If the recovered PbSO₄ is found to have a mass of 0.0471 g, what was the concentration of iodide ions in the original solution? A)3.10 * 10^-4 M B)1.55* 10^-4 M C)6.20 * 10^-3 M D)3.11 * 10^-3 M E)1.55 * 10^-3 M

Accepted Answer

First, we write out the balanced chemical equation for the reaction between H₂SO and PbI₂: H₂SO + PbI₂ -> PbSO₄ + HI This tells us that the amount of PbSO₄ formed in the reaction is directly proportional to the amount of H₂SO present in the solution. We can use this relationship to determine the moles of H₂SO present in the original solution, and from there the moles of iodide ions present. First, we calculate the moles of PbSO₄ formed: moles PbSO₄ = mass / molar mass moles PbSO₄ = 0.0471 g / 239.3 g/mol (molar mass of PbSO₄) moles PbSO₄ = 0.000197 mol Since the reaction is 1:1 between H₂SO and PbSO₄, this also gives us the moles of H₂SO present: moles H₂SO = 0.000197 mol Now we use the initial volumes and concentrations to calculate the initial moles of H₂SO: moles H₂SO = volume x concentration moles H₂SO = 0.0380 L x 0.1250 mol/L moles H₂SO = 0.00475 mol From here, we can use stoichiometry to find the moles of iodide ions: moles H₂SO : moles iodide ions = 1 : 1 moles iodide ions = 0.00475 mol Finally, we can use the initial volume to find the concentration of iodide ions: concentration = moles / volume concentration = 0.00475 mol / 0.100 L concentration = 0.0475 mol/L We need to convert this to scientific notation: concentration = 4.75 x 10^-2 mol/L And then to the requested format: Answer: D (3.11 x 10^-3 M) Therefore, the best choice for the concentration of iodide ions in the original solution is option D.

Question 20

A 0.9182 g sample of CaBr₂ is dissolved in enough water to give 500. mL of solution. What is the calcium ion concentration in this solution? A)9.19 * 10^-3 M B)2.30 * 10^-3 M C)2.72 * 10^-3 M D)4.59 * 10^-3 M E)1.25 * 10^-3 M

Accepted Answer

The answer of A 0.9182 g sample of CaBr₂ is...

Quiz 4: Reactions in Aqueous Solution

A 350. mL sample of 0.276M HNO₃ is partially neutralized by 125 mL of 0.0120M Ca(OH) ₂. Find the concentration of nitric acid in the resulting solution.

What mass of Na₂SO₄ is needed to prepare 350. mL of a solution having a sodium ion concentration of 0.125 M?

A 3.682 g sample of KClO₃ is dissolved in enough water to give 375. mL of solution. What is the chlorate ion concentration in this solution?

Which of the following represents an acid-base neutralization reaction?

Which of the following represents a precipitation reaction?

Which of the following represents a hydrogen displacement reaction?

Which of the following represents a combustion reaction?

What mass of K₂CO₃ is needed to prepare 200. mL of a solution having a potassium ion concentration of 0.150 M?

A 250. mL sample of 0.0328M HCl is partially neutralized by the addition of 100. mL of 0.0245M NaOH. Find the concentration of hydrochloric acid in the resulting solution.

A 20.00 mL sample of 0.1015 M nitric acid is introduced into a flask, and water is added until the volume of the solution reaches 250. mL. What is the concentration of nitric acid in the final solution?

When solid iron(II) hydroxide is added to water, the resulting solution contains 1.4 * 10^-3g of dissolved iron(II) hydroxide per liter of solution. What is the hydroxide ion concentration in this solution?

A 4.691 g sample of MgCl₂ is dissolved in enough water to give 750. mL of solution. What is the magnesium ion concentration in this solution?

A 50.0 mL sample of 0.436 M NH₄NO₃ is diluted with water to a total volume of 250.0 mL. What is the ammonium nitrate concentration in the resulting solution?

Which of the following represents a halogen displacement reaction?

Which of the following represents a metal displacement reaction?

What mass of Li₃PO₄ is needed to prepare 500. mL of a solution having a lithium ion concentration of 0.175 M?

A 0.9182 g sample of CaBr₂ is dissolved in enough water to give 500. mL of solution. What is the calcium ion concentration in this solution?

Quiz 4: Reactions in Aqueous Solution

A 350. mL sample of 0.276M HNO3 is partially neutralized by 125 mL of 0.0120M Ca(OH) 2. Find the concentration of nitric acid in the resulting solution.

What mass of Na2SO4 is needed to prepare 350. mL of a solution having a sodium ion concentration of 0.125 M?

A 3.682 g sample of KClO3 is dissolved in enough water to give 375. mL of solution. What is the chlorate ion concentration in this solution?