796295
Questão 1
Questão
What is the Relative formula mass (Mr) of CO (carbon monoxide)? Carbon=12, Oxygen=16.
Responda
-
28
-
192
Questão 2
Questão
What is the Relative atomic mass of a sodium atom?
Responda
-
11
-
23
Questão 3
Questão
What is the relative formula mass of sodium oxide (Na2O)? Ar sodium=23, Ar oxygen=16.
Responda
-
39
-
62
Questão 4
Questão
If you convert the relative atomic mass or the relative formula mass of an atom into grams, you get 1mole of the chemical.
Responda
- True
- False
Questão 5
Questão
What is the equation to find the % mass of an element in a compound?
Responda
-
% 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)
Questão 6
Questão
Take NaOH. What is the % mass of oxygen?
Responda
-
40%
-
65%
Questão 7
Questão
What is the empirical formula of a compound?
Responda
-
The smallest ratio of atoms present in a compound
-
Something that enables you to rule the world!
Questão 8
Questão
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
Responda
- True
- False
Questão 9
Questão
A compound is made from 72g carbon and 12g of hydrogen. What is its empirical formula?
Responda
-
C2H
-
CH2
Questão 10
Questão
How do you calculate moles?
Responda
-
m= n x M (m=mass, n=moles, M=molar mass)
-
M=n x m (m=mass, n=moles, M=molar mass)
Questão 11
Questão
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
Responda
- True
- False
Questão 12
Questão
What is the equation for working out the % yield?
Responda
-
% yield = maximum amount of product produced / minimum amount of product possible x100
-
% yield = amount of product produced / maximum amount of product possible x100
Questão 13
Questão
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.
Responda
-
80%
-
29.25%
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