15.5g of potassium nitrate is dissolved in 200cm 3 of water. How many moles of potassium nitrate are presented in 15.5g of the compound?

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Answer 1 · 2018-03-02T18:56:18

#"0.0075 mol"# #KNO_3#

FIRST

Look for the Molar mass of #KNO_3# = 101.10 g/mol

NEXT
Convert grams to moles:

#(15.5 g)/(101.10 "g/"mol")# = 0.1533 mol

Dissolved in 200 cc (0.2 L of water)

#("0.1533 mol"/"0.2 L")#

Assume Water density = 1 g/l

#"Total weight of compound" = 15.5 + 200 = 315.5 g#

Make the relation to find the moles of K:

#("0.1533 mol of K are dissolved in"/"315.5 g of compound"")#x#("15 g of compound")# =

#"0.0075 mol"# #KNO_3#