Question

Aqueous hydrobromic acid

HBr

will react with solid sodium hydroxide

NaOH

to produce aqueous sodium bromide

NaBr

and liquid water

H2O

.Suppose 42.9 g of hydrobromic acid is mixed with 34. g of sodium hydroxide. Calculate the minimum mass of hydrobromic acid that could be left over by the chemical reaction. Be sure your answer has the correct number of significant digits.

Answer 1

minimum mass of hydrobromic acid left = 0 g

Explanation

Balanced equation : HBr(aq) + NaOH(aq) NaBr(aq) + H₂O(l)

Case 1 : HBr is the limiting reactant

mass HBr = 42.9 g

moles HBr = (mass HBr) / (molar mass HBr)

moles HBr = (42.9 g) / (80.9 g/mol)

moles HBr = 0.530 mol

moles NaBr formed = moles HBr reacted

moles NaBr formed = 0.530 mol

Case 2 : NaOH is the limiting reactant

mass NaOH = 34 g

moles NaOH = (mass NaOH) / (molar mass NaOH)

moles NaOH = (34 g) / (40 g/mol)

moles NaOH = 0.850 mol

moles NaBr formed = moles NaOH reacted

moles NaBr formed = 0.850 mol

Since less moles of NaBr are formed in Case 1, therefore, HBr is the limiting reactant and all HBr is consumed.