Reactions 2

Question 1

How do u know a chemical reaction has happened

Answer 1

Change in temp, chnage in colour, change in mass, bubbles

Question 2

What is the balanced symbol equation for magnesium and oxygen reacting

Answer 2

2MG+O(small)2 ——> 2MgO

Question 3

Define catalyst

Answer 3

A chemical that speeds up a reaction by lowering the activation energy but it is not used up

Question 4

Define reactants

Answer 4

The chemicals that react together in a chemical reaction to form the products

Question 5

Define products

Answer 5

What is produced or formed in a chemical reaction

Question 6

Define combustion

Answer 6

A reaction where oxygen is reacted with a substance (hydrocarbon) to burn it. It forms water and carbon dioxide

Question 7

Define exothermic

Answer 7

A reaction that gives out energy into the surroundings. Increase in temp

Question 8

Define endothermic

Answer 8

A reaction where energy is taken in from the surroundings. Decrease in temp

Question 9

Word equation of magnesium and oxygen reacting

Answer 9

Magnesium+oxygen——> magnesium oxide

Question 10

Particle diagram showing magnesium and oxygen reacting

Answer 10

: + •-• ——> :=:

Question 11

What is the equation for combustion

Answer 11

Hydrocarbon+ oxygen —-> carbon dioxide+water

Question 12

Equation for incomplete combustion

Answer 12

Hydrocarbon+little to no oxygen ——-> carbon monoxide + water

Question 13

What is thermal decomposition

Answer 13

When a chemical substance (compound) breaks down (decomposes) into 2 or more chemical substances.

Question 14

Example of thermal decomposition

Answer 14

Calcium carbonate——-> calcium oxide + carbon dioxide

Question 15

What does conservation of mass mean

Answer 15

No atoms or destroyed or created. They are rearranged to form the products so the mass of the reactants and products is equal.

Question 16

Jessica used 0.24g of mag and put it in a Bb. at the end the product weighed 0.80g. What reacted with the mag and what was the mass of this?

Answer 16

Oxygen

0.56g

Question 17

What is bond energy

Answer 17

Energy to break bonds- energy to make bonds

Question 18

How to remember bond energy

Answer 18

Bendomexo

Question 19

Give an example of endothermic reaction

Answer 19

Ice pack have a drop in temp so they appear cold to soothe injuries. Energy is absorbed by the ice pack from the surroundings to make it appear cold. This makes is an endothermic reaction

Question 20

Give an example of an exothermic reaction

Answer 20

Combustion. Fuels such as methane react with oxygen completely to create water and carbon dioxide. this is called combustion and is an exothermic reaction bc energy is released into the surroundings causing a temp increase

Question 21

In an exothermic graph which is higher

Answer 21

Reactants are higher than products bc they have more energy

Question 22

In an endothermic Graph which is higher

Answer 22

Reactants are lower than products bc energy is taken i during the reaction

Question 23

Describe a reaction graph

Answer 23

Y axis is energy x axis is progress of reaction (time)

Question 24

Examples of thermal decomposition reactions

Answer 24

Heat
Copper carbonate ——> copper oxide + carbon dioxide

Sodium calcium lithium potassium

Question 25

Why does the mass apparat to decrease in a thermal decomposition reaction

Answer 25

When heated the compound break down, atoms change and carbon dioxide (g) is released. Gas moves freely in open systems (the air)

Question 26

In a Bond Energy equation, what does it mean if the answer is a negavtive

Answer 26

It means it is an exothermic reaction. if the number was positive it would be endothermic