The molar mass of sucrose (C12H22O11) is 342.3 g/mol. A chemist has a 0.500-mol sample of sucrose. What is the mass, in grams, of this sample?

a) 171

b) 342

c)500

d)684

a) 171

Explanation:

We can find the mass (in grams) of a sample by multiplying the amount of moles by the molar mass.

In this case, we know we have 0.500-mol and would multiply it by the molar mass, 342.3g/mol, to give us the answer of 171.15g rounded down to 171g.

Equation: 0.500mol x 342.3g/mol = 171.15g

number of molecules / avogadro's number * molecule molecular = mass

explanation:

we define a gram-molecular weight as the mass of one mole of any element or compound. a mole contains avogadro's number of units (molecules) –  

6.022

x

10

23

. so, dividing the number of molecules by avogadro's number gives us the number of moles. multiplying that by the molecular weight gives us the mass. from the periodic table we find the gram-molecular weight of u to be238 and of f to be19. so,  

u

f

6

will have a gram-molecular weight of 352g.