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Chemistry Unit 2

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Question 1 of 13

1

What is the Relative formula mass (Mr) of CO (carbon monoxide)? Carbon=12, Oxygen=16.

Select one of the following:

  • 28

  • 192

Explanation

Question 2 of 13

1

What is the Relative atomic mass of a sodium atom?

Select one of the following:

  • 11

  • 23

Explanation

Question 3 of 13

1

What is the relative formula mass of sodium oxide (Na2O)? Ar sodium=23, Ar oxygen=16.

Select one of the following:

  • 39

  • 62

Explanation

Question 4 of 13

1

If you convert the relative atomic mass or the relative formula mass of an atom into grams, you get 1mole of the chemical.

Select one of the following:

  • True
  • False

Explanation

Question 5 of 13

1

What is the equation to find the % mass of an element in a compound?

Select one of the following:

  • % mass of an element in a compound = Ar x number of atoms (of that element) / Mr (of whole compound)

  • % mass of an element in a compound = Ar x number of atoms (of whole compound) / Mr (of that element)

Explanation

Question 6 of 13

1

Take NaOH. What is the % mass of oxygen?

Select one of the following:

  • 40%

  • 65%

Explanation

Question 7 of 13

1

What is the empirical formula of a compound?

Select one of the following:

  • The smallest ratio of atoms present in a compound

  • Something that enables you to rule the world!

Explanation

Question 8 of 13

1

This is how you calculate the empirical formula of a compound:
1. Write down the mass of each element
2. Divide the mass by the relative atomic mass (Ar) of the element
3. Divide the numbers by the smallest number to get the ratio of elements
4. Put the ratios in their simplest forms

Select one of the following:

  • True
  • False

Explanation

Question 9 of 13

1

A compound is made from 72g carbon and 12g of hydrogen. What is its empirical formula?

Select one of the following:

  • C2H

  • CH2

Explanation

Question 10 of 13

1

How do you calculate moles?

Select one of the following:

  • m= n x M
    (m=mass, n=moles, M=molar mass)

  • M=n x m
    (m=mass, n=moles, M=molar mass)

Explanation

Question 11 of 13

1

This is how you calculate % yield:
1. Write out the equation
2. Balance the equation
3. Work out Mr for every reactant and product in the equation
4. Work out how many moles of reactant there are in the mass given in the question
5. Work out the mass of product you should make for 100% yield
6. Calculate % yield using the formula

Select one of the following:

  • True
  • False

Explanation

Question 12 of 13

1

What is the equation for working out the % yield?

Select one of the following:

  • % yield = maximum amount of product produced / minimum amount of product possible x100

  • % yield = amount of product produced / maximum amount of product possible x100

Explanation

Question 13 of 13

1

In an experiment, 11.5g of sodium is reacted with an excess of chlorine. The mass of sodium chloride made is 23.4g.
a) What is the maximum amount of product that could be made.
b) What is the % yield.

Select one of the following:

  • 80%

  • 29.25%

Explanation

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