Quiz 1A Answers
1) How many of each element elements are there in sulfuric acid? Sulfuric acid has the molecular formula of H2SO4.
There are 2 hydrogen atoms, 1 sulfur atom and four oxygen atoms.
2) How many of each element elements are there in sucrose? Sucrose has the molecular formula C12H22O11.
Sucrose contains 12 carbon atoms, 22 hydrogen atoms and 11 oxygen atoms.
3) What is the relative atomic mass of oxygen?
The relative atomic mass of oxygen is 16.
4) How many protons neutrons and electrons does oxygen have?
Oxygen has 8 protons, 8 neutrons and 8 electrons.
5) What is the relative atomic mass of carbon-12 and carbon 14? What is the difference between carbon-12 and carbon-14? How many neutrons does carbon-12 and carbon-14 have?
The relative atomic mass of carbon-12 is 12. The relative atomic mass of carbon-14 is 14. Carbon-12 and carbon-14 are both isotopes of carbon. Isotope are atoms of the same element that have the same number of protons and electrons but different numbers of neutrons. Carbon-12 has 6 neutrons and carbon-14 has 8 neutrons.
6) What is the relative formula mass of H2O. The relative atomic mass of hydrogen is 1 and the relative atomic mass of oxygen is 16.
The relative formula mass (Mr) of water is 18
(No of hydrogen atoms x Ar hydrogen) + (No of oxygen atoms x Ar oxygen)
(2 x 1) + (1 x 16) = 18
7) What is the relative atomic mass of magnesium chloride? Magnesium chloride is MgCl2. The relative atomic mass of magnesium is 24.3 and the relative atomic mass of chlorine is 35.5.
Mr of magnesium chloride is 95.3
(No of magnesium atoms x Ar magnesium) + (No of chlorine atoms x Ar chlorine)
(1 x 24.3) + (2 x 35.5) = 95.3
8) What is the relative formula mass of glucose? C6H12O6. Ar of carbon is 12, Ar of hydrogen is 1 and the Ar of oxygen is 16.
Mr of glucose is 180
(6 x 12) + (12 x 1) + (6 x 16)
9) What is the empirical formula of glucose? C6H12O6.
Empirical formula mass: CH2O
To find the empirical formula of glucose, we are looking for the simplest whole number ratio of atoms in a molecule/ compound. We obtain the empirical formula by dividing all of the atoms by the highest common multiple between all of the number. In glucose, there are 6 carbon atoms, 12 hydrogen atoms and 6 oxygen atoms. The highest common factor in 6, 12 and 6 is 6. Therefore, we divide all of these numbers by 6.
• Carbon – 6 ÷ 6 = 1
• Hydrogen – 12 ÷ 6 = 2
• Oxygen – 6 ÷ 6 = 1
This gives us the empirical formula for glucose of CH2O
10) How many of each element elements are there in Fe(NO3)3?
3 iron atoms, 3 nitrogen atoms (1 x 3) [1 is the number of nitrogen atoms inside the bracket and 3 is the number of brackets that there are] and 9 oxygen atoms (3 x 3)
11) What is the relative formula mass of Fe(NO3)3? Ar of Fe is 55.8, Ar of N is 14 and Ar of oxygen is 16.
Mr = 241.8
We multiply the number of atoms of each element by the relative atom mass of that element. (No of Fe x Ar Fe) + (No of N x Ar N) + (No of O x Ar O)
(1 x 55.8) + (3 x 14) + (9 x 16)
Mr = 241.8
There are 2 hydrogen atoms, 1 sulfur atom and four oxygen atoms.
2) How many of each element elements are there in sucrose? Sucrose has the molecular formula C12H22O11.
Sucrose contains 12 carbon atoms, 22 hydrogen atoms and 11 oxygen atoms.
3) What is the relative atomic mass of oxygen?
The relative atomic mass of oxygen is 16.
4) How many protons neutrons and electrons does oxygen have?
Oxygen has 8 protons, 8 neutrons and 8 electrons.
5) What is the relative atomic mass of carbon-12 and carbon 14? What is the difference between carbon-12 and carbon-14? How many neutrons does carbon-12 and carbon-14 have?
The relative atomic mass of carbon-12 is 12. The relative atomic mass of carbon-14 is 14. Carbon-12 and carbon-14 are both isotopes of carbon. Isotope are atoms of the same element that have the same number of protons and electrons but different numbers of neutrons. Carbon-12 has 6 neutrons and carbon-14 has 8 neutrons.
6) What is the relative formula mass of H2O. The relative atomic mass of hydrogen is 1 and the relative atomic mass of oxygen is 16.
The relative formula mass (Mr) of water is 18
(No of hydrogen atoms x Ar hydrogen) + (No of oxygen atoms x Ar oxygen)
(2 x 1) + (1 x 16) = 18
7) What is the relative atomic mass of magnesium chloride? Magnesium chloride is MgCl2. The relative atomic mass of magnesium is 24.3 and the relative atomic mass of chlorine is 35.5.
Mr of magnesium chloride is 95.3
(No of magnesium atoms x Ar magnesium) + (No of chlorine atoms x Ar chlorine)
(1 x 24.3) + (2 x 35.5) = 95.3
8) What is the relative formula mass of glucose? C6H12O6. Ar of carbon is 12, Ar of hydrogen is 1 and the Ar of oxygen is 16.
Mr of glucose is 180
(6 x 12) + (12 x 1) + (6 x 16)
9) What is the empirical formula of glucose? C6H12O6.
Empirical formula mass: CH2O
To find the empirical formula of glucose, we are looking for the simplest whole number ratio of atoms in a molecule/ compound. We obtain the empirical formula by dividing all of the atoms by the highest common multiple between all of the number. In glucose, there are 6 carbon atoms, 12 hydrogen atoms and 6 oxygen atoms. The highest common factor in 6, 12 and 6 is 6. Therefore, we divide all of these numbers by 6.
• Carbon – 6 ÷ 6 = 1
• Hydrogen – 12 ÷ 6 = 2
• Oxygen – 6 ÷ 6 = 1
This gives us the empirical formula for glucose of CH2O
10) How many of each element elements are there in Fe(NO3)3?
3 iron atoms, 3 nitrogen atoms (1 x 3) [1 is the number of nitrogen atoms inside the bracket and 3 is the number of brackets that there are] and 9 oxygen atoms (3 x 3)
11) What is the relative formula mass of Fe(NO3)3? Ar of Fe is 55.8, Ar of N is 14 and Ar of oxygen is 16.
Mr = 241.8
We multiply the number of atoms of each element by the relative atom mass of that element. (No of Fe x Ar Fe) + (No of N x Ar N) + (No of O x Ar O)
(1 x 55.8) + (3 x 14) + (9 x 16)
Mr = 241.8