Cooking And Chemical Change

Question 0

Give 4 reasons why we cook food

Answer 0

Improve taste and texture
Easier to digest
Kill off microbes that cause disease ( meat)
Kill off poison (kidney beans)

Question 1

Give 5 examples of cooking methods

Answer 1

Boiling
Frying
Steaming
Grilling
Oven
Microwave

Question 2

What is denaturing?

Answer 2

Protein molecules change shape when heated. Heat energy breaks chemical bonds, giving food more edible texture.
Eg. Raw eggs and meat YUK, cooked YUM (ish!)

Question 3

Why cook potatoes?

Answer 3

Potatoes (plants) have rigid cell walls made of cellulose - can’t digest.
Cooking ruptures cell walls and makes starch swell and spread.
Potatoe now softer and easier to digest.

Question 4

What happens to sodium bicarbonate when it is heated?

Answer 4

Thermal decomposition - breaks down into simpler substances.

Question 5

Equation for thermal decomposition of sodium hydrocarbonate

Answer 5

Sodium hydrocarbonate = sodium carbonate + carbon dioxide + water

2NaHCO3 = Na2CO3 + CO2 + H2O

Question 6

How do you test CO2 is formed when you heat baking powder?

Answer 6

Bubble gas through limewater - CO2 turns it cloudy.