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Multiple Choice
What is the molar mass of a 0.350 g sample of a HA acid if it requires 50.0 mL of 0.440 M Sr(OH)2 to completely neutralize it? A is used as a place holder for the unknown nonmetal of the acid.
A
15.9 g/mol
B
31.8 g/mol
C
5.30 g/mol
D
7.95 g/mol
Verified step by step guidance
1
Identify the balanced chemical equation for the neutralization reaction: HA + Sr(OH)_2 → SrA_2 + 2H_2O. This indicates that 2 moles of HA react with 1 mole of Sr(OH)_2.
Calculate the moles of Sr(OH)_2 used in the reaction. Use the formula: moles = concentration (M) × volume (L). Convert 50.0 mL to liters by dividing by 1000.
Determine the moles of HA that reacted. Since the stoichiometry of the reaction is 2:1, multiply the moles of Sr(OH)_2 by 2 to find the moles of HA.
Calculate the molar mass of HA. Use the formula: molar mass = mass of sample (g) / moles of HA. Substitute the given mass of the HA sample and the moles of HA calculated in the previous step.
Compare the calculated molar mass with the given options to identify the correct answer.