Question 1
Question
What is the Relative formula mass (Mr) of CO (carbon monoxide)? Carbon=12, Oxygen=16.
Question 2
Question
What is the Relative atomic mass of a sodium atom?
Question 3
Question
What is the relative formula mass of sodium oxide (Na2O)? Ar sodium=23, Ar oxygen=16.
Question 4
Question
If you convert the relative atomic mass or the relative formula mass of an atom into grams, you get 1mole of the chemical.
Question 5
Question
What is the equation to find the % mass of an element in a compound?
Answer
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% mass of an element in a compound = Ar x number of atoms (of that element) / Mr (of whole compound)
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% mass of an element in a compound = Ar x number of atoms (of whole compound) / Mr (of that element)
Question 6
Question
Take NaOH. What is the % mass of oxygen?
Question 7
Question
What is the empirical formula of a compound?
Question 8
Question
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
Question 9
Question
A compound is made from 72g carbon and 12g of hydrogen. What is its empirical formula?
Question 10
Question
How do you calculate moles?
Answer
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m= n x M
(m=mass, n=moles, M=molar mass)
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M=n x m
(m=mass, n=moles, M=molar mass)
Question 11
Question
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
Question 12
Question
What is the equation for working out the % yield?
Question 13
Question
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.