A student obtains the following data for an unknown crystalline compound
CHEMISTRY · Multi-part · A Level · Chemistry · Amount of substance · Amount of substance
Problem
A student obtains the following data for an unknown crystalline compound. Each trial involved weighing a fresh sample and determining its amount (in moles) by an independent method.
Number of moles (mol): 0.200, 0.400, 0.600, 0.800, 1.000
Mass (g): 10.41, 20.84, 31.28, 41.63, 52.07
Use the data to answer the questions that follow.
(a) Determine the molar mass of the unknown compound. Show your reasoning and report the value with the correct number of significant figures.
(b) Using your result from part (a), calculate the mass of compound required to contain 1.30 mol.
(c) A lab partner claims the substance is potassium chloride, KCl (molar mass 74.55 g mol⁻¹). Quantitatively assess this claim by calculating the percent difference between your experimental molar mass and the tabulated value, and state whether the claim is supported.