What is the number of moles of KF in a 29-gram sample of the compound?
(1) 1.0 mol
(2) 2.0 mol
(3) 0.50 mol
(4) 5.0 mol
Answer and Solution:
To find the number of moles, you can look at the reference table Table T and find the formula for moles.
Number of moles = given mass/ gram-formula mass
Therefore let's use first fine the gram formula mass by looking at the periodic table. K has a mass of 39g/mol and F is 18.998 g/mol. Therefore mass of KF = 39+18.998 = 57.998g/mol
this formula : Number of moles = 29g (mass given in the problem) / 57.998 g/mol = 0.5 moles Choice 3 is the correct choice.
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