A 3.555 g sample of a monoprotic acid was dissolved in water. It took 23.32 mL of a 0.875 M NaOH to neutralize the acid. Calculate the molar mass of the acid.
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To calculate the molar mass of the acid, we need to determine the number of moles of the acid that reacted with the NaOH.
First, let's find the number of moles of NaOH used. We can determine this by multiplying the volume of the NaOH solution (in liters) by its concentration (in moles per liter):
moles of NaOH = volume of NaOH (in liters) × concentration of NaOH (in moles per liter)
Given that the volume of NaOH used is 23.32 mL, we need to convert it to liters by dividing by 1000:
volume of NaOH = 23.32 mL ÷ 1000 = 0.02332 L
Substituting this value and the concentration of NaOH (0.875 M) into the equation, we get:
moles of NaOH = 0.02332 L × 0.875 mol/L = 0.02038 mol
Next, let's determine the number of moles of the acid. According to the balanced chemical equation between the acid and the base, the acid reacts in a 1:1 ratio with NaOH. This means that the number of moles of the acid is equal to the number of moles of NaOH:
moles of acid = moles of NaOH = 0.02038 mol
To calculate the molar mass of the acid, we can use the formula:
molar mass = mass of sample (in grams) / moles of acid
Given that the mass of the sample is 3.555 g and the number of moles of acid is 0.02038 mol, we can substitute these values into the equation:
molar mass = 3.555 g / 0.02038 mol ≈ 174.31 g/mol
Therefore, the molar mass of the acid is approximately 174.31 g/mol.