Relative formula mass

Multiple Choice

What does the second step in the process involve?

• Linking atomic masses

• Breaking down the formula

• Double-checking the work

• Calculating the total mass

Multiple Choice

What is the first step to calculate the relative formula mass of substances?

• Linking atomic masses from the Periodic Table

• Breaking down the formula

• Double-checking the work

• Using a calculator

Multiple Choice

What is the relative atomic mass defined as?

• The mass of an atom relative to 1/12th the mass of an atom of carbon-12

• The mass of an atom relative to the mass of hydrogen

• The mass of an atom relative to the mass of oxygen

• The mass of an atom relative to the mass of nitrogen

Multiple Choice

Which image shows the relative atomic mass (Ar) for fluorine?

• Image A

• Image B

• Image C

• None of the above

Multiple Choice

What is the correct method of calculating the M_r of CO_2?

• 12 + (2 x 8) = 28

• 12 + (2 x 16) = 44

• 16 + (2 x 12) = 40

• 12 + (2 x 12) = 36

Multiple Choice

What is the total relative formula mass (ΣM_r) of the reactants in the given chemical equation?

• 64

• 80

• 44

• 36

Open Ended

Using a periodic table, calculate the RFM (M_r) for the following compounds: hydrochloric acid (HCl), potassium hydroxide (KOH), sulfur dioxide (SO₂), nitrous oxide (N₂O), vanadium oxide (V₂O₅), hydrogen peroxide (H₂O₂), copper sulfate (CuSO₄), sulfuric acid (H₂SO₄), silver nitrate (AgNO₃), iron oxide (Fe₂O₃).

Multiple Choice

What is the relative formula mass (M_r) of the compound shown in image e)?

• 97 g/mol

• 110 g/mol

• 85 g/mol

• 120 g/mol

Multiple Choice

What is the relative formula mass (M_r) of the compound shown in image d)?

• 44 g/mol

• 58 g/mol

• 72 g/mol

• 30 g/mol

Open Ended

For the equation NaCl + AgNO₃ → NaNO₃ + AgCl, show that Σ M_r reactants = Σ M_r products.

Multiple Choice

If the M_r of the reactants is 120, what would the M_r of the products be?

• higher (over 120)

• the same (120)

• lower (less than 120)

Multiple Choice

For the equation NaCl + AgNO3 → NaNO3 + AgCl, show that Σ M_r reactants = Σ M_r products. What is the total relative formula mass of the reactants?

• 170.5

• 228.5

• 58.5

• 143.5

Multiple Choice

What is the percentage of carbon in carbon dioxide (CO2)?

• 12%

• 27.3%

• 44%

• 16%

Multiple Choice

To calculate the percentage by mass of an element in a compound you need to know ...

• the element’s atomic number only

• mass of element in compound only

• only the relative formula mass of the compound

• both the mass of element in compound and the relative formula mass of the compound

Open Ended

Are Sam and Andeep correct? Answers should be given to 1 d.p.

Multiple Choice

Calculate the % of hydrogen in methane CH₄. What is the % of hydrogen in methane?

• 12.5%

• 25.0%

• 50.0%

• 75.0%

Poll

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