Rates Of Reaction

Question 1

What does the graph for quantity of product formed (RoR Ch)
- what is on the y-axis
- what is on the x-axis
- shape of the curve

Answer 1

• Quantity of product formed in grams if solid/liquid and centimetres cubed if gas
• Time in Seconds
• rises quickly and curves off into a straight line horizontally.

Question 2

Why does the graph for quantity of products formed look like that? (RoR Ch)

Answer 2

• initially, reaction if very fast. Lots of product in short amount of time because of a large number of reactant molecules so lots are reacting and forming.
• gradually, the slope of the line becomes less steep. The reaction is slowing down. **Rate **of Reaction is decreasing because lots of the reactant molecules have already reacted and turned into product. Fewer reactant molecules available to react.
• Finally, the slope is now at zero. The line is flat so at this point the reaction has stopped. All molecules have already reacted.

Question 3

What does the graph for quantity of reactants present look like that (RoR Ch)
- what is on the y-axis
- what is on the x-axis
- shape of the curve

Answer 3

• Quantity of reactants in grams if solid/liquid and centimetres cubed if gas
• Time in Seconds
• Starts off decreasing quickly and starts to slow down until the reaction becomes a straight line.

Question 4

Why does the graph for quantity of reactants used up look like that? (RoR Ch)

Answer 4

• Initially the rate at which the curve is dropping is fast. Lots of reactants are being used up in a short amount of time because a large number of reacting molecules are forming into products Leaving less reactants.
• gradually the slope becomes less steep but is still going down .The rate of the reaction is decreasing because lots of molecules have already reacted so fewer reactants left.
• the slope is now at zero so all molecules have reacted leaving no reactants left behind.

Question 5

What is the unit for measuring the quantity of reactants/products used for solids and liquids? (RoR Ch)

Answer 5

Measure this in grams

Question 6

What is the unit for measuring the quantity of reactants/products used for gases? (RoR Ch)

Answer 6

Centimetres cubed

Question 7

What are the two ways of measuring rate of reaction?

Answer 7

• Using quantity of products formed
• Using quantity of reactants used

Question 8

What is the equation to find the mean rate of reaction for quantity of products formed? (QC Ch)

Answer 8

Quantity of product formed (cm cubed or g) divided by the time in seconds

Question 9

What is the equation to find the mean rate of reaction for quantity of reactants used up.

Answer 9

Quantity of reactant used up (cm cubed or g) divided by the time in seconds