chapter 14 rate of reactions

How do we measure the rate of reactions?

1. Volume of gas produced:

if a gas is produced in a reaction, we can measure the rate of reaction by measuring

the volume of gas given off in a fixed amount of time

Example

Reaction of marble chips (calcium carbonate) with dilute hydrochloric acid:

Calcium carbonate + hydrochloric acid → calcium chloride + water + carbon dioxide

CaCO3(s) + 2HCL(aq) → CaCL2 (aq) + H2O (l) + CO2 (g)

- we can find the rate of this reaction by measuring the volume of carbon dioxide

gas produced at regular time intervals

** can draw tangents at pts to determine steep vs gentle

2. Change in mass:

The mass of reactants decreases as they get used up, while the mass of products

increases.

- We can measure the rate of reaction by finding the change in mass of either the

reactants or products.

-reaction between marble chips (calcium carbonate) with dilute hydrochloric acid:

Since the carbon dioxide gas produced can escape to the surroundings, the mass of the

reaction mixture will decrease

-we can find the rate of reaction by measuring the change in mass of the reaction

mixture at regular time intervals

• Cotton wool -> prevent acid spray

What determines the rate of reactions?

Effective collisions: (5)

Factors affecting this:

Effect of concentration:

Effect of pressure (for gases only):

Effect of particle size

Effect of temperature