Chemistry B Final

When water is broken down into hydrogen and oxygen, the following reaction occurs. H₂O + H₂O ⟶ H₂O–H₂O ⟶ 2H₂ + O₂ The energy diagram of this reaction is shown. Which statement correctly describes the role of H₂O–H₂O, where it is depicted in the diagram, and the type of reaction?

• H₂O–H₂O is a product. It is shown in the diagram at A. The reaction is exothermic.

• H₂O–H₂O is a reactant. It is shown in the diagram at B. The reaction is endothermic.

• H₂O–H₂O is an activated complex. It is shown in the diagram at C. The reaction is exothermic.

• H₂O–H₂O is an activated complex. It is shown in the diagram at B. The reaction is endothermic.

Tags

NGSS.HS-PS1-4

What is the main purpose of performing a titration in a laboratory?

• To accurately measure the concentration of an acid or base.

• To create new acids and bases.

• To observe the boiling point of solutions.

• To evaporate water from a solution.

A group of students prepared the titration of a weak base and a strong acid. Before they started, they predicted the titration curve they expected to plot from the data of the experiment. Which titration curve would they expect to see if they were performing the titration of a weak base with a strong acid?

• Graph A

• Graph B

• Graph C

• Graph D

The inventory sheet said the laboratory had a 0.5M bottle of hydrochloric acid, a 0.2M bottle of hydrochloric acid, a 0.5M bottle of ethanoic acid, and a 0.2M bottle of ethanoic acid. To figure out which acid was which, the students tested the pH. Which acid would be expected to have the lowest pH if the same amount had evaporated from each bottle?

• 0.5M ethanoic acid

• 0.2M ethanoic acid

• 0.5M hydrochloric acid

• 0.2M hydrochloric acid

Which of the following options arranges the rocks, A, B, C, and D, in order of decreasing age, with the oldest rock on the far left and the youngest rock on the far right?

• A. B, C, D, A

• B. C, D, A, B

• C. D, C, A, B

• D. B, A, D, C

Tags

NGSS.HS-ESS1-5

A graph shows that the volume of a fixed mass of gas at a given temperature decreases as its pressure is increased. Which law does the graph most likely represent?

• Boyle's Law

• Charles's Law

• Avogadro's Law

• Gay-Lussac's Law

Is the reaction, BaCl₂(aq) + ZnSO₄(aq) → ZnCl₂(aq) + BaSO₄(s), a redox reaction or a non-redox reaction? Why?

• Redox reaction; the oxidation numbers of only the products change.

• Non-redox reaction; the oxidation numbers of only the reactants change.

Review the reaction between potassium dichromate and hydroiodic acid (HI in solution form).

K2Cr2O7(aq) + 4H2SO4(aq) + 6HI(aq) → K2SO4(aq) + Cr2(SO4)3(aq) + 3I2(s) + 7H2O(l)

What are the changes in oxidation numbers moving from the reactants to the products?

• Chromium changes from +6 to +3 and iodine changes from -1 to 0.

• Chromium changes from +3 to +6 and iodine changes from -1 to 0.

• Chromium changes from +6 to +3 and iodine changes from -1 to +1.

• Chromium changes from +3 to +6 and iodine changes from -1 to +1.

Tags

NGSS.HS-PS1-1

NGSS.HS-PS1-2

What process do scientists use to determine the age of objects on Earth?

• Measuring the size of the object

• Analyzing the isotopes present in the object

• Observing the color of the object

• Measuring the temperature of the object

Tags

NGSS.HS-ESS1-5

What is the half-life of Carbon-14 ?

• 5370 years

• 1000 years

• 25000 years

• 100000 years

Tags

NGSS.HS-PS1-8