Chemical calculations

Question 1

Naming Compounds

oxygen + iron –> ???

Answer 1

Iron oxide

non-metal + metal –> metal - non metal

Question 2

Two element compounds end in…?

Answer 2

ide

Question 3

Three element compounds containing oxygen end in…?

Answer 3

ate

Question 4

How to tell number of atoms in a formula?

Answer 4

It’s literally the small numbers lol noob gay

Question 5

Salt is also named…?

Answer 5

Uhh dude, that would be salt?

That’s what I said, sodium chloride

Question 6

What are ionic compounds made up in?

Answer 6

Two parts:
positive metal ion
negative non-metal ion

Question 7

How are all ionic compounds neutral?

Answer 7

Equal numbers of positive and negative charges

Question 8

What’s the chemical formula for sodium hydroxide?

Answer 8

Uhh idk, NaOH?

Question 9

How do u find the mass number?

Answer 9

Number at top of element

Question 10

How do u find the atomic number?

Answer 10

Number at bottom of element

Question 11

How do u find Mr? (molecule mass)

Answer 11

Add up mass numbers of the atoms (aka elements)

I guess just say
Add mass numbers of the singular element and multiply if more than 1 of em

Question 12

How do u calculate % of mass of an element?

percentage composition

Answer 12

1. Find the Mr of the compound
2. Find percentage of certain element by:
   Total amount of atoms of element/Total mass of compound x 100
   = percentage of element

Question 13

Balancing equations?

Answer 13

Reactants –> Products

Making sure both sides are balanced e.g.
2Li + 2HCl –> 2LiCl + H2

^^^ get it?

Question 14

List 3 signs of chemical change

Answer 14

· Effervescing
· Changes in state
· Temperature changes (increases/decreases)

Question 15

Define endothermic

Answer 15

Absorbs energy (decrease in temp)

Question 16

Define exothermic

Answer 16

Releases energy (increase in temp)

Question 17

Calculating Reacting Masses

List steps to find how much product is formed

Answer 17

1. Write balanced equation
2. Write Ar of each element
3. Write Mr of each compound
4. Total masses of reactants = total masses of products
5. Write in words what this means :(
   E.g.
   2Mg + O2 –> 2MgO
   2x24 + 2x16 –> 2x40
   48 + 32 –> 80
   48g + 32g = 80g
   48 grams of magnesium reacts with 32 grams of oxygen to produce 80 grams of magnesium oxide

^^^ wtf is all this

Question 18

Remember ‘Calculating Reacting Masses’?

How do u find how much magnesium oxide is produced from 1g of magnesium?

Answer 18

80 divided by 48 = 1.6?

^^^ idk if this right please correct or say below its right

Question 19

How to find 1g of a reactant?

Answer 19

Divide product by Reactant
e.g.
12g C burned in air, 44g of CO2 produced. Mass of C needed to produce 11g of CO2?
1g --> 3.7g (1dp)
11g --> 40.7g

Please just know what it generally means

Question 20

Calculating Formula by Experiment

Write the steps to find out the formula from the Ar values of the elements

Sulfure Ar = 32 Oxygen Ar = 16
3.2g of sulfur reacts with 6.4g of sulfur oxide. What is formula of the oxide?

Answer 20

1. Write element symbols | S and O
2. Write the masses | 3.2g and 6.4g - 3.2g = 3.2g
3. Write Ar values | 32 and 16
4. Divide masses by Ar | 3.2/32 = 0.1 and 3.2/16 = 0.2
5. Divide by smallest answer | 0.1/0.1 = 1 and 0.2/0.1 = 2
6. Write number of each atom | S and O2
7. Combine to give formula | SO2

^^^ yoo what is this shit nah this shit is gay

Question 21

How do u find percentage yield?

Answer 21

Yield = actual/theoretical x 100

e.g.

204 tonnes of aluminium oxide are expected to produce 108 tonnes of aluminium.
Only 81 tonnes are actually made. Find percentage yield.

81/108 x 100 = 75%

Question 22

How to find 1g of an element?

Answer 22

Total Mr of product divided by total Mr of starting material

^^^ I’m not remembering any of that

Question 23

How do u find the number of moles?

Answer 23

Mass (g) ÷ Mr (molecular mass)