Question

Vitamin B12, cyanocobalamin, is essential for human nutrition. It is concentrated in animal tissue but not in higher plants. Although nutritional requirements for the vitamin are quite low, people who abstain completely from animal products may develop a deficiency anemia. Cyanocobalamin is the form used in vitamin supplements. It contains 4.34% cobalt by mass. Calculate the molar mass of cyanocobalamin, assuming that there is one atom of cobalt in every molecule of cyanocobalamin. WebAssign will check your answer for the correct number of significant figures. g/mol

Answer 1

645 g/mol

Step-by-step explanation:

Step 1: Given data

Percent by mass of cobalt in cyanocobalamin: 4.34%

Step 2: Determine the molar mass of cyanocobalamin

There is one atom of cobalt in every molecule of cyanocobalamin, or what is the same, there is 1 mole of atoms of Co in every mole of molecules of cyanocobalamin. Given the molar mass of Co is 28.01 g/mol, the molar mass of cyanocobalamin is:

100 g B12/4.34 g Co × 28.01 g Co/1 mol Co × 1 mol Co/1 mol B12 = 645 g/mol