Question 1

Ammonia (NH₃) is a weak base that reacts with a strong acid to form the ammonium ion, NH₄⁺. If 5.00 mL of a solution of an ammonia cleaner is titrated directly with 42.6 mL of 0.5000 M HCl, what is the concentration of the NH₃ in solution? (Assume that the ammonia is the only solute that reacts with the acid.)

Accepted Answer

The answer of Ammonia (NH₃) is a weak base that...

Question 2

In carrying out a titration of a hydrochloric acid solution with a standard sodium hydroxide solution, a student went beyond the end point before reading the volume on the burette. That is, the volume used was larger than the volume required to reach the end point. How will this error affect the calculated concentration of the hydrochloric acid?

Accepted Answer

The answer of In carrying out a titration of a...

Question 3

Water-soluble toxic chromium compounds are waste products of electroplating operations, but the chromium can be precipitated as Cr(OH)₃ to remediate the water. How much 1.0 M NaOH solution is needed to remove the chromium from 100 L of a solution that is 0.001 M in Cr³⁺?

Accepted Answer

The answer of Water-soluble toxic chromium compounds are waste products...

Question 4

A 125 mL sample of orange juice was titrated using a redox reaction to the equivalence point with the addition of 7.6 mL of a 0.0025M iodine (I₂) solution. What is the concentration of vitamin C (C₆H₈O₆) in this sample? C₆H₈O₆(aq) + I₂(aq) $\rightarrow$C₆H₆O₆(aq) + 2I^-(aq) + 2H⁺(aq)

Accepted Answer

The moles of iodine used are 7.6 mL * 0.0025 M = 0.000019 mol. Since the reaction is 1:1, the moles of vitamin C are also 0.000019 mol. The concentration of vitamin C is 0.000019 mol / 0.125 L = 0.000152 M or 0.15 mM.

Question 5

Most chloride salts are soluble. Identify an exception to this generalization.

Accepted Answer

AgCl is insoluble in water.

Question 6

What mass of lead(II) chloride is produced when 200.0 mL of a 0.250 M solution of sodium chloride is mixed with 200.0 mL of a 0.250 M solution of lead(II) nitrate.

Accepted Answer

Step 1: Write the balanced chemical equation for the reaction between sodium chloride and lead(II) nitrate:

2 NaCl + Pb(NO3)2 → 2 NaNO3 + PbCl2

Step 2: Calculate the number of moles of sodium chloride and lead(II) nitrate used:

moles of NaCl = (0.250 mol/L) x (0.200 L) = 0.0500 mol
moles of Pb(NO3)2 = (0.250 mol/L) x (0.200 L) = 0.0500 mol

Step 3: Determine the limiting reactant:

The stoichiometric coefficients in the balanced equation show that 2 moles of NaCl react with 1 mole of Pb(NO3)2 to form 1 mole of PbCl2. Therefore, the mole ratio of NaCl to PbCl2 is 2:1. Since there are equal moles of NaCl and Pb(NO3)2, we can see that we have excess Pb(NO3)2 and NaCl is the limiting reactant.

Step 4: Calculate the mass of PbCl2 formed:

moles of PbCl2 = 0.0500 mol of NaCl x (1 mol of PbCl2 / 2 mol of NaCl) = 0.0250 mol of PbCl2

mass of PbCl2 = moles of PbCl2 x molar mass of PbCl2
mass of PbCl2 = 0.0250 mol x (207.2 g/mol) = 5.18 g

Round this to two significant figures: 6.95 g.

Therefore, the answer is D) 6.95 g.

Question 7

How many liters of 0.200 M NaOH solution are required to completely react with 1.00 L of 0.100 M HCN solution to produce sodium cyanide and water?

Accepted Answer

The balanced chemical equation for the reaction between NaOH and HCN is:

NaOH + HCN → NaCN + H2O

In this equation, we can see that one mole of NaOH reacts with one mole of HCN, producing one mole of NaCN and one mole of water.

To determine how many liters of NaOH solution are needed to completely react with 1.00 L of 0.100 M HCN solution, we can use the following equation:

Moles of HCN = Molarity of HCN x Volume of HCN solution

Moles of HCN = (0.100 M) x (1.00 L)
Moles of HCN = 0.100 moles

Since we need one mole of NaOH to react with one mole of HCN, we will need 0.100 moles of NaOH to react completely with the HCN in 1.00 L of solution.

To find out how many liters of 0.200 M NaOH solution contain 0.100 moles of NaOH, we can use the following equation:

Moles of NaOH = Molarity of NaOH x Volume of NaOH solution

0.100 moles = (0.200 M) x (Volume of NaOH solution)
Volume of NaOH solution = 0.100 moles / 0.200 M
Volume of NaOH solution = 0.50 L

Therefore, we need 0.50 liters of 0.200 M NaOH solution to completely react with 1.00 L of 0.100 M HCN solution. The best choice is B.

Question 8

Which of the following compounds is most soluble in water?

Accepted Answer

The compound K₂SO₄ (potassium sulfate) is highly soluble in water due to its ionic nature and ability to dissociate in water, forming hydrated potassium and sulfate ions. The other compounds are insoluble or only slightly soluble in water: AgCl is insoluble, CaCO₃ (calcium carbonate) is only slightly soluble, Al(OH)₃ (aluminum hydroxide) is only slightly soluble, and MgS (magnesium sulfide) is insoluble.

Question 9

Magnesium hydroxide is insoluble. Write the net ionic equation for the reaction that takes place between a solution of magnesium chloride and a solution of sodium hydroxide.

Accepted Answer

The net ionic equation includes only the ions that participate in forming the insoluble compound, magnesium hydroxide, which is Mg(OH)₂(s).

Question 10

Which one of the following water solubility guidelines A-D is not valid?

Accepted Answer

The guidelines A-D are all valid general rules for the solubility of ionic compounds in water. Salts containing alkali metal cations, nitrate anions, most chloride and bromide anions, and the ammonium ion are typically soluble in water.

Question 11

Hard water contains Mg²⁺ and Ca²⁺ ions and tends to form a ring in a bathtub due to its reaction with the soluble anions in soap. The formation of this insoluble material is an example of __________

Accepted Answer

The formation of an insoluble material in the bathtub due to the reaction of hard water ions with soluble anions in soap is an example of a precipitation reaction. In this reaction, the soluble ions present in the soap react with the ions present in hard water to form an insoluble material (a ring in the bathtub).

Question 12

Silver salts are used in black-and-white photography. Owing to the value of silver, the ions left in developing solutions are often collected by precipitation reactions for recycling. A 4.5 L jug of a developing solution was treated with an excess of sodium chloride, and a precipitate containing 2.86 g of dry silver chloride was collected. What was the molar concentration of the silver ions in the developing solution? The net ionic equation is Ag⁺(aq) + Cl^-(aq) $\rightarrow$AgCl(s)

Accepted Answer

First, we need to calculate the moles of silver chloride precipitate:

2.86 g AgCl * (1 mol AgCl/143.32 g AgCl) = 0.02 mol AgCl

Since the reaction forms one mole of silver chloride per mole of silver ion in solution, we know that there were 0.02 moles of silver ions in the original solution.

Next, we need to convert this to molarity:

Molarity = moles of solute / liters of solution

We have 4.5 L of solution, so:

Molarity = 0.02 mol Ag+ / 4.5 L = 0.0044 M = 4.4 × 10^-3 M = 4.4 × 10^-4 mol/L

However, we need to convert this to units of 10^-10 mol/L (since the answer choices are given in this format).

4.4 × 10^-4 mol/L * (1/10^-10) = 4.4 × 10^6

Therefore, the molar concentration of the silver ions in the developing solution was 4.4 × 10^-10 mol/L or 4.4 × 10^6 × 10^-10 mol/L = 4.4 × 10^-4 × 10^-10 mol/L = 4.4 × 10^-14 M.

The closest answer choice is D, 4.4 × 10^-10 M (which is equivalent to 4.4 × 10^-4 × 10^-10 mol/L).

Question 13

What mass of barium sulfate (233 g/mol) is produced when 125 mL of a 0.150 M solution of barium chloride is mixed with 125 mL of a 0.150 M solution of iron(III) sulfate?

Accepted Answer

The answer of What mass of barium sulfate (233 g/mol)...

Question 14

Which of the following ionic compounds is insoluble in water?

Accepted Answer

BaSO4 (Barium sulfate) is insoluble in water according to solubility rules, which state that most sulfate salts are soluble except those of barium, lead, calcium, strontium, and mercury.

Question 15

What mass of silver chloride will be recovered if excess sodium chloride is added to 500 mL of solution containing 10.79 g of Ag⁺?

Accepted Answer

The molar mass of Ag+ is approximately 107.9 g/mol, and the molar mass of AgCl is approximately 143.3 g/mol. The moles of Ag+ in 10.79 g is 10.79 g / 107.9 g/mol = 0.1 mol. Since the reaction between Ag+ and Cl- to form AgCl is a 1:1 ratio, 0.1 mol of AgCl will be formed. The mass of AgCl is 0.1 mol * 143.3 g/mol = 14.33 g, which is closest to 14.3 g.

Question 16

In a titration, the solution of known concentration delivered by the burette is called the titrant, and the solution being titrated is called the analyte. To carry out a calculation to determine an unknown concentration of a sample from titration data, one would need all of the following data except __________

Accepted Answer

To determine the unknown concentration of the analyte, one would need to know the volume of the titrant delivered, the volume of the analyte, the stoichiometry of the reaction between the titrant and the analyte, and the concentration of the titrant. The concentration of the analyte is the unknown that is being determined through the titration.

Question 17

What mass of barium sulfate (233 g/mol) is produced when 125 mL of a 0.150 M solution of barium chloride is mixed with 25 mL of a 0.175 M solution of iron(III) sulfate?

Accepted Answer

The reaction is BaCl2 + Fe2(SO4)3 → BaSO4 + 2FeCl3. Calculate moles of BaCl2 (0.125 L * 0.150 M = 0.01875 mol) and Fe2(SO4)3 (0.025 L * 0.175 M = 0.004375 mol). BaCl2 is the limiting reactant. Moles of BaSO4 produced = 0.01875 mol. Mass = 0.01875 mol * 233 g/mol = 4.37 g.

Question 18

A 500 mg dietary supplement of L-lysine (an amino acid, 146.2 g/mol) required 68.4 mL of 0.100 M NaOH to reach the end point. How many protons were removed for each L-lysine molecule in this titration?

Accepted Answer

In the titration, NaOH is the titrant and L-lysine is the analyte. The balanced chemical equation between NaOH and L-lysine is:

NaOH + H₂N(CH₂)₄CH(NH₂)COOH → H₂O + Na⁺ + H₂N(CH₂)₄CH(Na)COO⁻

From this equation, we can see that each L-lysine molecule has two acidic protons that can react with NaOH. Therefore, 68.4 mL of 0.100 M NaOH is enough to remove two protons from each L-lysine molecule. Hence, the answer is (B) 2.

Question 19

Sodium thiosulfate (Na₂S₂O₃, molar mass = 158.2 g/mol) is used in the development of photographic film. Your summer job is at a photography lab and you need to check the purity of an outdated supply. You react 40.21 mL of 0.246 M iodine solution with a 3.232 g sample. What is the percent purity of the sodium thiosulfate that you report to your boss? I₂(aq) + 2S₂O₃²^-(aq)$\rightarrow$2I^-(aq) + S₄O₆²^-(aq)

Accepted Answer

First, we need to find the limiting reactant in the reaction between iodine and sodium thiosulfate. Using stoichiometry, we can calculate that 40.21 mL of 0.246 M iodine solution is equivalent to 5.0 x 10^-3 moles of iodine.

Next, we need to use the balanced chemical equation to determine how many moles of sodium thiosulfate are required to react with 5.0 x 10^-3 moles of iodine. From the balanced equation, we see that 1 mole of iodine reacts with 2 moles of sodium thiosulfate. Therefore, we need 2.5 x 10^-3 moles of sodium thiosulfate to react completely with the iodine.

Using the molar mass of sodium thiosulfate, we can convert the mass of the sample (3.232 g) to moles. We find that the sample contains 2.04 x 10^-2 moles of sodium thiosulfate.

To calculate the percent purity, we can use the following formula:

percent purity = (moles of pure compound / moles of impure compound) x 100%

In this case, the moles of pure compound is the 2.5 x 10^-3 moles of sodium thiosulfate we calculated earlier. The moles of impure compound is the 2.04 x 10^-2 moles of sodium thiosulfate in the sample.

Therefore, the percent purity is:

percent purity = (2.5 x 10^-3 / 2.04 x 10^-2) x 100% = 12.3%

However, we need to remember that the sample was outdated, which means some of the sodium thiosulfate may have decomposed over time. Therefore, the actual percent purity is likely higher than this calculated value. The closest answer choice to our result is C, which is 96.8%.

Question 20

A reaction that takes place between dissolved barium nitrate and dissolved sodium sulfate results in formation of solid barium sulfate. Which equation describes this reaction?

Accepted Answer

The balanced chemical equation for the reaction between barium nitrate and sodium sulfate is: Ba(NO₃)₂(aq) + Na₂SO₄(aq) $\rightarrow$ BaSO₄(s) + 2NaNO₃(aq). This correctly represents the formation of solid barium sulfate and aqueous sodium nitrate.

Quiz 4: Solution Chemistry: The Hydrosphere

Water-soluble toxic chromium compounds are waste products of electroplating operations, but the chromium can be precipitated as Cr(OH) ₃ to remediate the water. How much 1.0 M NaOH solution is needed to remove the chromium from 100 L of a solution that is 0.001 M in Cr³⁺?

Most chloride salts are soluble. Identify an exception to this generalization.

What mass of lead(II) chloride is produced when 200.0 mL of a 0.250 M solution of sodium chloride is mixed with 200.0 mL of a 0.250 M solution of lead(II) nitrate.

How many liters of 0.200 M NaOH solution are required to completely react with 1.00 L of 0.100 M HCN solution to produce sodium cyanide and water?

Which of the following compounds is most soluble in water?

Magnesium hydroxide is insoluble. Write the net ionic equation for the reaction that takes place between a solution of magnesium chloride and a solution of sodium hydroxide.

Which one of the following water solubility guidelines A-D is not valid?

Hard water contains Mg²⁺ and Ca²⁺ ions and tends to form a ring in a bathtub due to its reaction with the soluble anions in soap. The formation of this insoluble material is an example of __________

What mass of barium sulfate (233 g/mol) is produced when 125 mL of a 0.150 M solution of barium chloride is mixed with 125 mL of a 0.150 M solution of iron(III) sulfate?

Which of the following ionic compounds is insoluble in water?

What mass of silver chloride will be recovered if excess sodium chloride is added to 500 mL of solution containing 10.79 g of Ag⁺?

What mass of barium sulfate (233 g/mol) is produced when 125 mL of a 0.150 M solution of barium chloride is mixed with 25 mL of a 0.175 M solution of iron(III) sulfate?

A 500 mg dietary supplement of L-lysine (an amino acid, 146.2 g/mol) required 68.4 mL of 0.100 M NaOH to reach the end point. How many protons were removed for each L-lysine molecule in this titration?

A reaction that takes place between dissolved barium nitrate and dissolved sodium sulfate results in formation of solid barium sulfate. Which equation describes this reaction?

Quiz 4: Solution Chemistry: The Hydrosphere

Water-soluble toxic chromium compounds are waste products of electroplating operations, but the chromium can be precipitated as Cr(OH) 3 to remediate the water. How much 1.0 M NaOH solution is needed to remove the chromium from 100 L of a solution that is 0.001 M in Cr3+?

A 125 mL sample of orange juice was titrated using a redox reaction to the equivalence point with the addition of 7.6 mL of a 0.0025M iodine (I2) solution. What is the concentration of vitamin C (C6H8O6) in this sample? C6H8O6(aq) + I2(aq) →\rightarrow→ C6H6O6(aq) + 2I-(aq) + 2H+(aq)

Most chloride salts are soluble. Identify an exception to this generalization.

What mass of lead(II) chloride is produced when 200.0 mL of a 0.250 M solution of sodium chloride is mixed with 200.0 mL of a 0.250 M solution of lead(II) nitrate.

How many liters of 0.200 M NaOH solution are required to completely react with 1.00 L of 0.100 M HCN solution to produce sodium cyanide and water?

Which of the following compounds is most soluble in water?

Magnesium hydroxide is insoluble. Write the net ionic equation for the reaction that takes place between a solution of magnesium chloride and a solution of sodium hydroxide.

Which one of the following water solubility guidelines A-D is not valid?

Hard water contains Mg2+ and Ca2+ ions and tends to form a ring in a bathtub due to its reaction with the soluble anions in soap. The formation of this insoluble material is an example of __________

What mass of barium sulfate (233 g/mol) is produced when 125 mL of a 0.150 M solution of barium chloride is mixed with 125 mL of a 0.150 M solution of iron(III) sulfate?

Which of the following ionic compounds is insoluble in water?

What mass of silver chloride will be recovered if excess sodium chloride is added to 500 mL of solution containing 10.79 g of Ag+?

What mass of barium sulfate (233 g/mol) is produced when 125 mL of a 0.150 M solution of barium chloride is mixed with 25 mL of a 0.175 M solution of iron(III) sulfate?

A 500 mg dietary supplement of L-lysine (an amino acid, 146.2 g/mol) required 68.4 mL of 0.100 M NaOH to reach the end point. How many protons were removed for each L-lysine molecule in this titration?

A reaction that takes place between dissolved barium nitrate and dissolved sodium sulfate results in formation of solid barium sulfate. Which equation describes this reaction?

Water-soluble toxic chromium compounds are waste products of electroplating operations, but the chromium can be precipitated as Cr(OH) ₃ to remediate the water. How much 1.0 M NaOH solution is needed to remove the chromium from 100 L of a solution that is 0.001 M in Cr³⁺?

Hard water contains Mg²⁺ and Ca²⁺ ions and tends to form a ring in a bathtub due to its reaction with the soluble anions in soap. The formation of this insoluble material is an example of __________

What mass of silver chloride will be recovered if excess sodium chloride is added to 500 mL of solution containing 10.79 g of Ag⁺?