Unit 4 Test
If 0.40 mol of H2 and 0.15 mol of O2 were to react as completely as possible to produce H2O, what mass of reactant would remain?
0.20g of H2
Which of the following is the balanced net ionic equation for an oxidation-reduction reaction between Ag (aq) and Ni (aq) based on the half-reactions represented above?
2 Ag+ (aq) + Ni (s) --> 2Ag (s) + Ni2+ (aq)
If equal masses of the following compounds undergo complete combustion, which will yield the greatest mass of CO2?
Benzene, C6H6
The diagrams above represent solutes present in two different dilute aqueous solutions before they were mixed. Water molecules are not shown. When the solutions were combined, a precipitation reaction took place. Which of the diagrams below is the best particle representation of the mixture after the precipitation reaction occurred?
D
Potassium hydrogen phthalate, KHP, is used as a primary standard for determining the concentration of a solution of NaOH by titration. If the KHP has not been dried before weighing, the calculated molarity of the NaOH would be?
Higher than the actual value, since water is included in the apparent mass of KHP
Which of the following is the conjugate acid of NH2?
NH3
Which element is being oxidized during the titration, and what is the element's change in oxidation number?
Oxygen, which changes from -1 to 0
A 2 mol sample of F2 (g) reacts with excess NaOH (aq) according to the equation above. If the reaction is repeated with excess NaOH (aq) but with 1 mol of F2 (g), which of the following is correct?
The amount of OF2 (g) produced is halved
At 127 degrees celsius, the entire sample of I2 is observed to have vaporized. How does the mass of vessel 5 at 127 degrees celsius compared to its mass at 27 degrees celsius?
The mass is the same, since the number of each type of atom in the vessel is a constant
A student places a sample of a pure metal in a crucible and heats it strongly in air. Data from the experiment are given in the table above. The final mass was determined after the sample was cooled to room temperature. Which of the following statements related to the experiment is correct?
The mass of the sample increased, so a chemical change occurred when bonds formed between the metal and another substance
A student asked to formulate a hypothesis about what would happen if 100.0 mL of 0.1 M NaOH (aq) at 25 degrees celsius was combined with 100.0 mL of 0.1 M MgCl2 (aq) at 25 degrees celsius. Which of the following hypothesis indicates that the student thought a chemical change would occur?
The resulting solution would contain a precipitate
A solution of a salt of a weak acid HY is added to a solution of another weak acid HX. Based on the information given above, which of the following species is the strongest base?
Y- (aq)
