Question

Now use the molar masses of the products to determine the mass of each solid required for the titration. 15. What mass of NaOH is required to react with 0.01853 mol HCl? 16. What mass of Na2CO3 is required to react with 0.01853 mol HCl? 17. What mass of Na2O is required to react with 0.01853 mol HCl? In Test 2 you will react the solid product with a slight excess of HCl, boil off the water, and collect and measure the solid NaCl. Suppose you take 0.9900 g of the solid product. Now that you have done a few stoichiometric calculations we will ask directly for you to perform mass-mass calculations. Remember that along the way you will need to determine the number of moles and use the balanced equations above. 18. With 0.9900 g of NaOH and excess HCl, what mass of NaCl could be formed? 19. With 0.9900 g of Na2CO3 and excess HCl, what mass of NaCl could be formed? 20. With 0.9900 g of Na2O and excess HCl, what mass of NaCl could be formed?

Answer 1

Ans15. Mass of NaOH is required to react with 0.01853 mol HCl.

A pertinent balanced chemical reaction between NaOH and HCl is,

NaOH + HCl NaCl + H₂O

Mole relationship is

1 mol NaOH 1 mol HCl

Hence,

# of moles of NaOH required = # of moles of HCl

# of moles of NaOH required = 0.01853 mol .......... (# of moles of HCl given)

Now, molar mass of NaOH = 40.0 g/mol

Mass of 0.01853 mole NaOH = # of moles of NaOH * Molar mass of NaOH

                                               = 0.01853 mol * 40.0 g/mol

                                               = 0.7412 g

Mass of NaOH required is 0.7412 g.

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Ans16. Mass of Na2CO3 is required to react with 0.01853 mol HCl

A pertinent reaction is

Na2CO3 + 2 HCl 2 NaCl (aq) + H2CO3 (Unstabl) 2 NaCl (aq) + H2O (l) + CO2 (g).

Mole relationship is

1 mol Na2CO3 2 mole HCl

# of moles of Na2CO3 required = 1/2 * # of moles of HCl = 1/2 * 0.01853 = 0.009265 mol.

# of moles of Na2CO3 required = 0.009265 mol

Molar mass of Na2CO3 = 106.0 gmol

Mass of 0.009265 mol Na2CO3 = 0.009265 mol * 106.0 g/mol = 0.982 g

Mass of Na2CO3 required is 0.982 g.

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Ans17. Mass of Na2O is required to react with 0.01853 mol HCl

A pertinent reaction is

Na2O + 2 HCl 2 NaCl (aq) + H2O (l).

Mole relationship is

1 mol Na2O 2 mole HCl

# of moles of Na2O required = 1/2 * # of moles of HCl = 1/2 * 0.01853 = 0.009265 mol.

# of moles of Na2O required = 0.009265 mol

Molar mass of Na2O = 62.0 gmol

Mass of 0.009265 mol Na2O = 0.009265 mol * 62.0 g/mol = 0.574 g

Mass of Na2O required is 0.574 g.

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