Question

Barium can be analyzed by precipitating it as BaSO4, and determining the mass of the

precipitate. When a 0.269 g sample of mixture containing Ba(NO3)2 was treated with excess
Na2SO4, 0.0891 g of BaSO4 formed. What is the mass percentage of barium nitrate in the
compound?
Ba(NO3)2(aq) + Na2SO4(aq) → BaSO4(s) + 2 NaNO3(aq)

Answer 1

To find the mass percentage of barium nitrate in the compound, we can use the following steps:

Step 1: Write the balanced chemical equation for the reaction. We are given the equation as:

Ba(NO3​)2​(aq) + Na2​SO4​(aq) → BaSO4​(s) + 2 NaNO3​(aq)

Step 2: Calculate the moles of BaSO4 formed using the mass and the molar mass. We are given the mass of BaSO4 as 0.0891 g. The molar mass of BaSO4 is 233.39 g/mol1. We can use the formula:

moles of BaSO4​=molar mass of BaSO4​mass of BaSO4​​

We can substitute the values and simplify:

moles of BaSO4​=233.39 g/mol0.0891 g​

moles of BaSO4​=0.000382 mol

Step 3: Calculate the moles of Ba(NO3)2 that reacted using the mole ratio from the balanced equation. We can see that one mole of Ba(NO3)2 produces one mole of BaSO4, according to the equation. Therefore, the mole ratio is 1:1. We can use the formula:

moles of Ba(NO3​)2​=moles of BaSO4​×coefficient of BaSO4​coefficient of Ba(NO3​)2​​

We can substitute the values and simplify:

moles of Ba(NO3​)2​=0.000382 mol×11​

moles of Ba(NO3​)2​=0.000382 mol

Step 4: Calculate the mass of Ba(NO3)2 that reacted using the moles and the molar mass. The molar mass of Ba(NO3)2 is 261.34 g/mol1. We can use the formula:

mass of Ba(NO3​)2​=moles of Ba(NO3​)2​×molar mass of Ba(NO3​)2​

We can substitute the values and simplify:

mass of Ba(NO3​)2​=0.000382 mol×261.34 g/mol

mass of Ba(NO3​)2​=0.0998 g

Step 5: Calculate the mass percentage of Ba(NO3)2 in the compound using the mass of Ba(NO3)2 and the total mass of the compound. We are given the total mass of the compound as 0.269 g. We can use the formula:

mass percentage of Ba(NO3​)2​=total mass of compoundmass of Ba(NO3​)2​​×100%

We can substitute the values and simplify:

mass percentage of Ba(NO3​)2​=0.269 g0.0998 g​×100%

mass percentage of Ba(NO3​)2​=37.10%

Therefore, the mass percentage of barium nitrate in the compound is 37.10 %.