CB 4-2 review

Which of the following best models a weak acid in aqueous solution? (Water molecules are not included.)

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Which of the following correctly compares the concentration of H⁺ in solution 1 with a pH of 4.6 and the concentration of H⁺ in a solution 2 that is naturally acidic and has a pH of 5.6?

• The H⁺ concentration in the solution 1 is 2 times higher than the H⁺ concentration in the solution2.

• The H⁺ concentration in the solution 1 is 4.6 times higher than the H⁺ concentration in the solution 2

• The H⁺ concentration in the solution 1 is 10 times higher than the H⁺ concentration in the solution 2

A student is given a concentrated solution that is supposed to contain vinegar, a weak acid. Which of the following experimental tests would best support the claim that the solution is a weak acid rather than a strong acid?

• Measure the pH and find it is close to 7.

• Test the electrical conductivity and find it is low.

• Observe a vigorous reaction with metals.

• Find that it completely dissociates in water.

Which of the following is the approximate pH of the solution represented in the particle diagram? pH = - log [H+]

• 0

• 0.3

• 1

• 2

A student combines equal volumes of 1.0 M aqueous solutions of hydrochloric acid and sodium hydroxide. The equation for the reaction is shown. The student places the resulting solution in an evaporating dish and heats it on a hot plate. Which of the following substances will remain in the evaporating dish once all the water has evaporated?

• HCl(s)

• NaOH(s)

• H₂O(s)

• NaCl(s)

Tags

NGSS.HS-PS1-2

For the given hypothetical reaction, which of the following best describes how the temperature changes as the reaction progresses and why?

• The temperature increases because more energy is released when the new bonds in the product form than is absorbed when the bonds in the reactant break.

• The temperature increases because more energy is absorbed when the new bonds in the product form than is released when the bonds in the reactant break.

• The temperature decreases because more energy is released when the new bonds in the product form than is absorbed when the bonds in the reactant break.

• The temperature decreases because more energy is absorbed when the new bonds in the product form than is released when the bonds in the reactant break.

Tags

NGSS.HS-PS1-4

A student conducts a series of experiments involving the reaction of H₂(g) with I₂(g). Particle representations of three different reaction conditions in containers of equal volume are shown. For each Figure, circle the correct rate description: fastest, intermediate, or slowest to rank the order of reaction rates.

• Figure 1: Slowest,

  Figure 2: Fastest,

  Figure 3: Intermediate

• Figure 1: Fastest,

  Figure 2: Intermediate,

  Figure 3: Slowest

• Figure 1: Intermediate,

  Figure 2: Fastest,

  Figure 3: Slowest

• Figure 1: Fastest,

  Figure 2: Slowest,

  Figure 3: Intermediate

Tags

NGSS.HS-PS1-5

Which of the following statements about the chemical reaction is best supported using the data from the experiment?

• The reaction is exothermic because the temperature of the water increased during the reaction.

• The reaction is exothermic because the mass of the mixture increased during the reaction.

• The reaction is endothermic because the temperature of the water increased during the reaction.

• The reaction is endothermic because the mass of the mixture increased during the reaction.

Tags

NGSS.HS-PS1-4

NGSS.HS-PS3-4

A student performs a calorimetry experiment. The student combines 100. g of 0.40 M HCl (aq) with 100. g of 0.40 M NaOH (aq). Data are given in the table. The value of q for the experiment is closest to which of the following? (Assume that the heat capacity of the solution is the same as the heat capacity of water, Cp = 4.18 J/g^oC)

• 560 J

• 1200 J

• 2300 J

• 5900 J

Tags

NGSS.HS-PS1-4

NGSS.HS-PS3-4

Two 1 L solutions are represented in the particle diagrams. Select the solution with the higher pH. Then, select the reasoning that best supports the claim.

• Solution A

• Solution B

• It has a lower concentration of H+ ions.

• It has a higher concentration of H+ ions.