Answers 25-26 KCS18 Chemistry ICUnit Test

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What type of substance reacts with limestone (CaCO3) and produces carbon dioxide gas?

a neutral substance

a base

an acid

both an acid and a base

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A number of beakers have different concentrations of a solution. Which statement best describes the most concentrated solution?

It has the largest volume.

It has the most solute for a given volume.

It has the greatest amount of solute.

It has the most volume for a given amount of solute.

Soaps feel slippery on our hands because they dissolve the oil on our skin, decreasing friction.This is because soap contains

a neutral molecule.

a salt molecule.

an acid.

a base.

The molality of a solution that is made by dissolving a certain mass of ethanol in 85.4 g of water is 0.950 m. How many moles of ethanol were dissolved?Use .

0.0811 mol

0.0899 mol

11.1 mol

81.1 mol

Which of these correctly defines the pOH of a solution?

the log of the hydronium ion concentration

the negative log of the hydronium ion concentration

the log of the hydroxide ion concentration

the negative log of the hydroxide ion concentration

Which solute, an electrolyte or a nonelectrolyte, has the greater effect on the boiling point when a given amount of each solute is dissolved in the same mass of water?

The nonelectrolyte does because it disperses into molecules.

The electrolyte does because it disperses into molecules.

The nonelectrolyte does because it dissociates into ions.

The electrolyte does because it dissociates into ions.

A government laboratory wants to determine whether water in a certain city has any traces of fluoride and whether the concentration exceeds the recommended 4.00 ppm. A 5.00-g sample of this water is found to have 0.152 mg of fluoride. Should the water be declared safe for drinking?Use .

3.04 ppm < 4.00 ppm, safe to drink

7.60 ppm > 4 ppm, safe to drink

A. 30.4 ppm > 4 ppm, unsafe to drink

30,400 ppm > 4 ppm, unsafe to drink

What is the relationship between the concentration of particles in a solution and the solution’s vapor pressure?

As solute concentration increases, vapor pressure increases.

As solute concentration increases, vapor pressure decreases.

As the concentration of electrolytes increases, vapor pressure increases. However, as the concentration of nonelectrolytes increases, vapor pressure decreases.

As the concentration of electrolytes increases, vapor pressure decreases. However, as the concentration of nonelectrolytes increases, vapor pressure increases.

Which of the following substances is an Arrhenius acid?

BF3

HCN

NH3

Mg(OH)2

In a coffee shop, the following coffee samples are prepared for customers.i. 10 g of sugar added to 100 g of coffeeii. 10 g of sugar added to 200 g of coffeeiii. 4 g of sugar added to 200 g of coffeeiv. 4 g of sugar added to 100 g of coffeeBased on the amount of sugar added, which sequence ranks the coffee from the sweetest coffee to the least-sweet coffee?

i, ii , iii, iv

iii, iv, ii, i

iv, i, ii, iii

i, ii, iv, iii

Lewis acids and bases are most closely associated with which process?

proton transfer

electron transfer

the formation of aqueous ions

the formation of a conjugate acid or base

Which description correctly characterizes the acidity or basicity of a solution?

The higher the pH is, the more the hydroxide ion concentration decreases and the more acidic the solution becomes.

The higher the pH is, the more the hydroxide ion concentration increases and the more basic the solution becomes.

The lower the pH is, the more the hydronium ion concentration decreases and the more acidic the solution becomes.

The lower the pH is, the more the hydronium ion concentration increases and the more basic the solution becomes.

What mass of solid that has a molar mass of 46.0 g/mol should be added to 150.0 g of benzene to raise the boiling point of benzene by 6.28°C? (The boiling point elevation constant of benzene is 2.53°C•kg/mol.)Use .

2.48 g

8.25 g

17.1 g

43.3 g

Consider the reaction below.NH4+ + H2O NH3 + H3O+Which is an acid-conjugate base pair?

NH4+ and NH3

NH4+ and H3O+

H2O and NH3

H2O and H3O+

What is the molality of a solution that is obtained by dissolving 2.922 g of NaCl into 1000.0 g of water if the molar mass of NaCl is 58.44 g/mol?Use .

0.05000 m

2.922 m

5.856 m

20.00 m

A 250-mL aqueous solution contains 1.56 10–5 g of methanol and has a density of 1.03 g/mL. What is the concentration in ppm?Use .

6.1 10-8 ppm

1.5 10-5 ppm

0.061 ppm

15 ppm

What is the definition of a Lewis base?

a substance that donates a proton

a substance that donates electrons to form a covalent bond

a substance that accepts electrons to form a covalent bond

a substance that when dissolved in water increases hydrogen ion concentration

An unknown substance turns blue litmus paper to red. Which additional test could be used to confirm the substance’s identity?

It should turn phenolphthalein from colorless to pink because it is a base.

It should turn phenolphthalein from pink to colorless because it is a base.

It should turn methyl orange to orange because it is an acid.

It should turn methyl orange to red because it is an acid.

Which pair of substances would most likely result in the production of a gas when reacting with an acid?

litmus and methyl orange

base and salt

metal and carbonate

carbon dioxide and water

What mass of solid that has a molar mass 89.0 g/mol should be added to 100.0 g of benzene to raise the boiling point of benzene by 2.42°C? (The boiling point elevation constant of benzene is 2.53°C•kg/mol.)Use .

2.84 g

8.52 g

21.5 g

93.0 g

A solution of ammonia has a pH of 11.8. What is the concentration of OH– ions in the solution?Useful formulas include , , , and .

1.58 10–12 M

6.31 10–3 M

2.20 M

158 M

A solution of HCl has = 0.01 M. What is the pH of this solution?Use .

–2

–1

Given that the molar mass of NaCl is 58.44 g/mol, what is the molarity of a solution that contains 87.75 g of NaCl in 500. mL of solution?Use .

0.333 M

0.751 M

1.50 M

3.00 M

A 1.00 L volume of HCl reacted completely with 2.00 L of 1.50 M Ca(OH)2 according to the balanced chemical equation below.2HCl + Ca(OH)2 CaCl2 + 2H2OWhat was the molarity of the HCl solution?

0.375 M

1.50 M

3.00 M

6.00 M

Note the pH and pOH values labeled with letters on the pH scale below.Based on log rules and the way pH is calculated, what is the difference in [OH– ] concentration between point A and point B.

101

105

106

107

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