Chemical Reactions Test RETAKE

Choose the reaction that will have the faster rate:

• 2.75 grams of sodium bicarbonate in 50 mL of vinegar.

• 18.9 grams of sodium bicarbonate in 50 mL of vinegar.

Which of the following is a combustion reaction?

• 2H₂ + O₂ → 2H₂O

• CH₄ + 2O₂ → CO₂ + 2H₂O

• Fe + O₂ → Fe₂O₃

• NaCl → Na + Cl₂

The higher the concentration of the reactants in a reaction will ________________ the rate of reaction

• Increase

• Decrease

• Leave the same

What type of Chemical reaction is this? 2Cu + O2 -> 2CuO

• Double Replacement

• Decomposition

• Synthesis

• Combustion

Decreasing the temperature in a chemical reaction will ______ the rate of a chemical reaction.

• Decrease

• Increase

• Have no effect

• Double

Match the factor that can affect the rate of chemical reaction to its correct description.

• Used to decrease the amount of energy needed to cause a reaction

• Temperature

• The heat energy involved in a reaction

• Concentration

• The size of the particles can affect the rate of a reaction

• Surface Area

• The amount of reactants involved in the reaction

• Catalyst

What is the role of a catalyst in a chemical reaction?

• It is consumed in the reaction and permanently changes the products.

• It increases the amount energy required for the reaction.

• It speeds up the reaction without being consumed in the process.

• It decreases the temperature of the reaction.

The graph below shows the temperature changes occurring in two hot packs that are made from different materials. The same amounts of water and CaCl2 were used to make each pack. Which of the following inferences is supported by the graph?

• Latex is a better conductor than LDPE.

• During a 60-minute time period, LDPE will release less energy to its surroundings than latex.

• LDPE would be the best choice for a hand warmer designed to release heat quickly.

• The LDPE pack reaches its maximum temperature sooner than the latex pack.

An Alka-Seltzer tablet is added to 25 mL of water. Which of these experimental changes would change the rate to make the chemical reaction of the Alka-Seltzer tablet go slower?

• Heat the water to a warmer temperature.

• Add ice to the water to lower its temperature.

• Break the tablet into smaller pieces.

• Use less than 25 mL of water.

Endothermic reactions absorb heat, making the surroundings warmer.

• True

• False