0973 06 Chemical Reactions - Rates SUPPLEMENT

Front

Define rate of reaction.

Back

The amount of reactant used up per second

Front

What's the formula to calculate the mean rate of reaction in terms of reactants used?

Back

(quantity of reactant used) ÷ (time taken)

Front

What's the formula to calculate the mean rate of reaction in terms of product formed?

Back

(quantity of product formed) ÷ (time taken)

Front

What are the two possible units for rate of reaction?

Back

g/s or cm³/s (where s is seconds)

Front

How can you tell the fastest rate of reaction from graphs of 'volume of product formed' against 'time'?

Back

The graph with the steepest gradient is the fastest.

Front

How can you tell a reaction has completed from a graph of 'volume of product formed' against 'time'?

Back

When the gradient becomes zero (a straight horizontal line).

Front

What is a tangent?

Back

A straight line that touches a curve at a point but doesn't cross the curve

Front

How can the rate of a reaction be shown at a point in time on a graph?

Back

by drawing a tangent

Front

How can the rate of a reaction at a point in time be calculated from a graph?

Back

1. Draw a tangent on the graph at the point in time 2. Rate of reaction = gradient of the tangent = change in y ÷ change in x

Front

Why does the rate of a reaction decrease over time?

Back

because the number of reactant particles available to react decreases as they are turned into products