chemical reactions Flashcards
Which of the following is a chemical reaction?
a) Melting ice
b) Boiling water
c) Rusting iron
d) Dissolving sugar in water
C (rusting iron)
What is the product when magnesium reacts with oxygen?
a) Magnesium oxide
b) Magnesium chloride
c) Magnesium sulphate
d) Magnesium nitrate
A (magnesium oxide)
Which of the following is an example of a combustion reaction?
a) Photosynthesis
b) Respiration
c) Rusting
d) Burning wood
D (burning wood)
Define a chemical change.
a (usually reversible) change that does not lead to the formation of a new substance
define a physical change
a (usually reversible) change that doesn’t lead to the formation of a new substance
name the three components of the fire triangle
heat, fuel and oxygen
complete the equation:
fuel+ oxygen→
carbon dioxide+energy
julie lights a candle and puts a glass over it and the flame goes out. is this complete or incomplete combustion
the fire runs out of oxygen. incomplete combustion
what two forms of energy does combustion give out
heat and light
what is aerobic resperation
the conversion of glucose and oxygen into carbon dioxide and water
what is anaerobic respiration
the incomplete breakdown of glucose without oxygen to produce ATP
what is the word equation for anaerobic respiration
glucose → lactic acid
what is fermentation used for
to make items such as bread and beer
what is the word equation for fermentation
glucose → ethanol + carbon dioxide
define rusting
the corrosion of iron
what is the chemical name for rust
hydrated iron oxide
what is the word equation for rusting
iron + water+ oxygen→ hydrated iron oxide
what can you do to prevent rusting
- coat with plastic
- galvanising (coating with zinc)
- oiling/ greasing
- painting
julie does an experiment. she takes three test tubes and puts a nail in each one to see which one rusts the most
test tube 1: empty (oxygen, no water)
test tube 2: half full with salt water (oxygen, salt and water)
test tube 3: half full with water (oxygen, water)
which one rusts the most and why
test tube 2 rusts the most because it has all the things needed for rusting to occur and salt speeds up the reaction
true or false:
the law of conservation states :
mass of reactant > mass of product
false the law of conservation states that mass of reactant=mass of product
julie does an experiment with 9g of magnesium chloride and some hydrogen. after the experiment the product weighed 12g. according to the law of conservation, how much does the hydrogen weigh?
(12g - 9g =) 3g
julie does an experiment with baking soda and vinegar. some of the product remains and some of it escapes into the atmosphere as a gas. was julies experiment a closed or open system
open system
julie does an experiment. she lights a candle in a bottle and puts a balloon on top to trap the product in the bottle. was julies experiment a closed or open system
closed system
what does ? represent:
20g of chlorine + 60g of oxygen → 45g of carbon dioxide + ? of water
20 + 60 = 80
80 - 45 = 35
? = 35 g
true or false:
a new substance is made in a chemical reaction
true
what does ? represent in:
total mass of reactant = ?
total mass of product
can you destroy an atom
no- atoms cant be created or destroyed
why must chemical equations be balanced
because atoms cant be created or destroyed
