HELP 1. A chemical needs 0.22 moles CaO for a chemical reaction. How many grams of CaO do they need to obtain that amount?

2. What is the mass of 0.83 moles of NaCl?

3. For an acid-base titration, 0.5 moles of H2SO4 will be needed. How many grams of H2SO4 were needed for the Laboratory Activity?

Explanation:

1.

 Given parameters:

Number of moles of CaO = 0.22moles

Unknown:

Mass of CaO = ?

Solution:

Mass, number of moles and molar mass are related using the expression below;

  Mass  = number of moles x molar mass

Molar mass of CaO  = 40 + 16  = 56g/mol

  Insert the parameters and solve;

  Mass = 0.22 x 56  = 12.32g

2

Given parameters:

Number of moles of NaCl  = 0.83moles

Unknown:

mass of NaCl  = ?

Solution:

Also,

 Mass  = number of moles x molar mass

Molar mass of NaCl = 23 + 35.5 = 58.5g/mol

Now insert the parameters and solve;

    mass = 0.83 x 58.5

     mass  = 48.6g

3.

Given parameters:

Number of moles of H₂SO₄  = 0.5moles

Unknown:

mass of H₂SO₄ = ?

Solution:

Mass  = number of moles x molar mass

Molar mass of H₂SO₄  = 2(1) + 32 + 4(16) = 98g/mol

Insert the parameters and solve;

  Mass = 0.5 x 98  = 49g

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