1) We observe that 35.2 mL of H2SO4 (98.1 g/mol) solution reacts with 0.355 gram

Question

1) We observe that 35.2 mL of H2SO4 (98.1 g/mol) solution reacts with 0.355 grams of Na2CO3 (105.99 g/mol): H2SO4 + Na2CO3 Na2SO4 + H2O + CO2 What is the molarity of the H2SO4 solution? Answer in units of mol/L.

2) How many milliliters of a 0.9 molar HCl solution are needed to react completely with 6 grams of zinc according to the following equation? ? HCl + ? Zn ? ZnCl2 + ? H2 Answer in units of mL.

3) We add excess NaCl solution (58.44 g/mol) to 49 mL of a solution of silver nitrate (AgNO3 169.88 g/mol), to form insoluble solid AgCl. When it has been dried and weighed, the mass of AgCl (143.32 g/mol) is found to be 2.37 grams. What is the molarity of the original AgNO3 solution? The formula weight of NaNO3 is 85.00 g/mol. Answer in units of M.

4) We add excess Na2CrO4 solution to 23.0 mL of a solution of silver nitrate (AgNO3) to form insoluble solid Ag2CrO4. When it has been dried and weighed, the mass of Ag2CrO4 is found to be 0.120 grams. What is the molarity of the AgNO3 solution? Answer in units of M.

Explanation / Answer

1) molar mass of Na2CO3 = 105.99 g/mol then 0.355 gm of Na2CO3 = 0.355 / 105.99 = 0.003349 mole

reaction between Na2CO3 and H2SO4 is

Na2CO3 + H2SO4 ------> Na2SO4 + H2CO3

according to reaction 1 mole of Na2CO3 react with 1 mole of H2SO4 then to react with 0.003349 mol of Na2CO3 required H2SO4 = 0.003349 mole

Molarity = no. of mole/volume of solution in lliter

molarity of  H2SO4 = 0.003349 / 0.0352 = 0.095 M

2) Balanced reaction is

Zn + 2HCl -------.> ZnCl2 + H2

molar mass of Zn = 65.38 gm/mole then 6 gm of zinc = 6/65.38 = 0.09177 mole

According to reaction 1mole of Zn react with 2 mole of HCl therefore to react with 0.09177 mole of zinc required HCl = 0.09177 X 2 = 0.1835 mole

volume of solution in liter = no. of mole / molarity

molarity of HCl = 0.1835 / 0.9 = 0.2039 M

3) balanced chemical reaction is

NaCl + AgNO3 -----> AgCl + NaNO3

molar mass of AgCl = 143.32 g/mole then 2.37 gm = 2.37 / 143.32 = 0.016536 mole

According to reaction 1 mole of AgNO3 produce 1 mole of AgCl then to produce 0.016536 mole of AgCl required AgNO3 = 0.0136536 mole

molarity = no. of mole/ volume of solution in liter

Molarity of AgNO3 = 0.0136536 / 0.049 = 0.337 M

4) balanced chemical equation is

2AgNO3 + Na2CrO4 ------> Ag2CrO4 + 2NaNO3

molar mass of Ag2CrO4 = 331.73 gm/mol then 0.120 gm = 0.120/331.73 = 0.00036174 mole

According to reaction 2 mole AgNO3 produce 1 mole Ag2CrO4 then to produce 0.00036174 required AgNO3 is 0.0036173 X 2 = 0.00072348 mole

molarity = no. of mole/ volume of solution in liter

Molarity of AgNO3 = 0.00072348 / 0.023 = 0.0315 M

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