Rates of reaction- Methods to measure the rate (L1)

Which of the following are practical methods used to determine the rate of reaction?

• Gas collection, loss of mass, and precipitation

• Gas collection and color change

• Loss of mass and temperature change

• Precipitation and pH change

The particle theory explains changes of rate as a result of changes in temperature, concentration (pressure), and surface area by describing how:

• particles move faster and collide more frequently at higher temperatures, increasing the rate of reaction.

• particles move slower and collide less frequently at higher temperatures, decreasing the rate of reaction.

• particles remain unaffected by changes in temperature, concentration, or surface area.

• particles only change their speed but not their collision frequency.

Investigate the factors that affect the rate of a reaction using a gas collection method.

• Temperature, concentration, and surface area

• Color and odor of reactants

• Volume of container

• Type of gas collected

What factors can alter the speed of the reaction between sodium thiosulfate and dilute hydrochloric acid?

• Concentration of sodium thiosulfate

• Temperature of the solution

• Use of a catalyst

• All of these factors

Complete the table to explain what happens to the mass when 10g of magnesium ribbon is burnt in oxygen. Why doesn’t it always appear that the mass of the reactants equals the mass of the products?

• The mass of the products is greater due to the addition of oxygen.

• The mass of the products is less due to the loss of magnesium.

• The mass remains the same as the reactants.

• The mass of the reactants is greater due to the loss of oxygen.

Complete the table to explain what happens to the mass when 25g of hydrochloric acid has 3g of powdered marble added to it, and a gas escapes. Why doesn’t it always appear that the mass of the reactants equals the mass of the products?

• The mass of the reactants is always equal to the mass of the products because mass is conserved.

• The mass of the reactants appears less than the mass of the products because some mass is lost as gas.

• The mass of the reactants appears more than the mass of the products because some mass is lost as gas.

• The mass of the reactants is always more than the mass of the products because mass is not conserved.

Complete the table to explain what happens to the mass when 25g of water has 5g of salt added to it and is stirred until all the salt dissolves. Why doesn’t it always appear that the mass of the reactants equals the mass of the products?

• The mass of the solution is 30g, but it may appear less due to evaporation or measurement errors.

• The mass of the solution is 25g, as the salt does not contribute to the mass.

• The mass of the solution is 5g, as only the salt is considered.

• The mass of the solution is 50g, as the mass doubles after mixing.

In the experiment where a can of lemonade is opened and left for 4 hours, what happens to the mass?

• The mass increases

• The mass appears to decrease

• The mass stays the same.

Precipitation can be used to measure the rate of a reaction by:

• observing the time it takes for a precipitate to form

• measuring the temperature change during the reaction

• calculating the change in pH

• monitoring the color change of the solution

The volume of gas given off (gas collection) can be used to measure the rate of a reaction by:

• measuring the time taken to collect a certain volume of gas

• measuring the temperature change during the reaction

• observing the color change of the reactants

• measuring the mass of the reactants before and after the reaction