[3N Sci Chem] Chemical Calculations

​Chemical Calculations

Multiple Choice

In this lesson, Mr Teoh will not be around. Please promise to complete this lesson on your own and try your best! Please also read all feedback after each question!

• Okay, I will be self-directed.

• How about, no... =(

Fill in the Blanks

Multiple Choice

Please also take out your notes for Chemical Calculation.

• Yes I took out already.

• I will be taking it out.

​Let's recall!

Multiple Choice

What is the relative atomic mass of oxygen atom?

• 1

• 8

• 16

• 32

Let's recall!

Match

Match the following substances to their correct relative molecular mass.

• oxygen atom

• oxygen molecule (O₂)

• sodium hydroxide (NaOH)

• water

• fluorine gas

16

32

40

18

38

• 16

• 32

• 40

• 18

• 38

In this chapter, you will need a bit of Mathematics.
Complete the quiz questions to recap.

Math Response

How many socks are there in one pair of socks?

Type answer here

Correct Answer: 2

Deg^°

Rad

Math Response

How many socks are there in 10 pairs of socks?

Type answer here

Correct Answer: 20

Deg^°

Rad

Math Response

How many eggs are there in one dozen of eggs?

Type answer here

Correct Answer: 12

Deg^°

Rad

Multiple Choice

How many dozen of eggs are there in this picture?

• 1

• 6

• 0.5

• 12

Multiple Choice

Below is an example of an equation:

a = b × c

What is c?

• c = a × b

• c = a ÷ b

• c = b ÷ a

Multiple Choice

A packet of peanut weighs 200 g.

Each peanut weighs approximately 1.5 g.

How many peanuts are there in the packet?

• number of peanuts = 200 ÷ 1.5

• number of peanuts = 1.5 ÷ 200

• number of peanuts = 200 × 1.5

What is mole?

What is mole?

If I have 6 × 10²³ socks (that is a lot a lot of socks!), I can say that there are 1 mol of socks.

What is mole?

If I zoom in and count the number of particles in this gold bar, I counted 12 × 10²³ particles, I can say that there are 2 mol of gold atoms.

If I zoom in and count the number of particles in this carbon , I counted 3 × 10²³ particles, I can say that there are 0.5 mol of carbon atoms.

What is mole?

1 mol of magnesium oxide (MgO) contains 1 mol of magnesium ions and 1 mol of oxide ions. Therefore, there are a total of 2 mol of ions.

Let's Practice Page 5

​Once completed, check your answer on the next page!

Check your answers!

Multiple Choice

Elephants are large mammals. Mice are small mammals. Elephants are afraid of mice.

 

If I have 1000 elephants and 1000 mice, are there more elephants or more mice?

• More elephants

• More mice

• Same number

Multiple Choice

I weigh my elephants and mice.

 

If I have 10 000 kg of elephants and 10 000 kg of mice. Which are heavier?

• 10 000 kg of elephants are heavier.

• 10 000 kg of mice are heavier.

• Both have the same mass.

Multiple Choice

I weigh my elephants and mice and count the number of elephants and mice I have.

 

If I have 10 000 kg of elephants and 10 000 kg of mice. Do I have more elephants or more mice?

• More elephants

• More mice

• Same number of elephants as mice

Multiple Choice

I want to find out the number of elephants in 10 000 kg. Each elephant weighs 1000 kg.

Which of the following shows the relation between 1. mass of elephants 2. number of elephants and 3. mass per elephant?

• number of elephants = mass of elephants × mass of each elephant

• number of elephants = mass of elephants ÷ mass of each elephant

• number of elephants = mass of each elephant ÷ mass of elephants

Multiple Choice

1 mol of carbon atoms weigh 12 g (This is the Ar of carbon!)

I have a container with 48 g of carbon atoms. What is the number of mol of carbon atoms?

• number of mol of carbon atoms = 48 g ÷ 12 g per mol

• number of mol of carbon atoms = 12 g per mol ÷ 48 g

• number of mol of carbon atoms = 48 g × 12 g per mol

Let's summarise!

Task:
- Complete the rest of the SLS assignment.
- Practise the questions in Page 8 of the notes!