Past paper questions

Question 1

What’s 3 differences between endothermic and exothermic reactions

Answer 1

1.Endothermic: Absorbs energy (usually heat) from the surroundings.
Exothermic: Releases energy (usually heat) into the surroundings.

2.Endothermic: The surroundings become cooler as the reaction absorbs heat.
Exothermic: The surroundings become warmer as the reaction releases heat

3.Endothermic: ΔH[enthalpy change] is positive,exothermic its negative

Question 2

How to find out if a reaction is exothermic or endothermic

Answer 2

Neutralizations of acids with bases is exothermic also if the graph has an increase its exothermic

Question 3

What happens when a metal and acid react

Answer 3

A salt and hydrogen gas form.
eg. Mg + 2HCl → MgCl2 + H2

Question 4

How to calculate number of moles

Answer 4

Mass[grams]/molar mass
[M/MM]
or mm/m

OR

Number of particles/Avogadro’s number[6.022x 10^23)

Question 5

How to determine volume of gas at stp

Answer 5

Number of moles of the gas x 22.4 L/mol

Question 6

How to calculate energy[enthalpy] change

Answer 6

m x c x ∆t

m=mass of substance
∆T=represents the change in temperature (final temperature minus initial temperature).
c=specific heat capacity

Question 7

What is an alloy

Answer 7

A mixture of two or more metals

Question 8

What are 3 types of steel

Answer 8

Carbon steel
Stainless steel
Alloy steel

Question 9

What are some enhanced properties of steel

Answer 9

Increased Strength
Corrosion resistant
Heat resistant

Question 10

Whats decomposition reaction vs synthesis

Answer 10

one reactant breaks down into two or more products.
Synthesis is when one combine

Question 11

Whats a single replacement reaction

Answer 11

one element is substituted for another element in a compound. [starting is always a pure element]

AB plus C= AC plus B
or A plus BC=AC plus B

Question 12

Whats a double replacement

Answer 12

Have two ionic compounds that are exchanging anions or cations.
AB + CD → AD + CB