몰농도 계산. A reagent bottle is labeled 0.255 M K2SO4

몰농도 계산. A reagent bottle is labeled 0.255 M K2SO4

 

 

A reagent bottle is labeled 0.255 M K2SO4.

a. How many moles of K2SO4 are present in 25.0 mL of this solution?

b. How many mL of this solution are required to supply 0.0600 mol of K2SO4?

c. Assuming no volume change, how many grams of K2SO4 do you need to add to 1.50 L of this solution to obtain a 0.800 M solution of K2SO4?

d. If 40.0 mL of the original solution are added to enough water to make 135 mL of solution, what is the molarity of the diluted solution?

 

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a. (0.255 mol/L) * 0.0250 L = 0.006375 mol = 0.00638 mol

( 계산 설명 http://ywpop.tistory.com/7787 )

 

 

b. 0.0600 mol / (0.255 mol/L) = 0.235294 L = 235 mL

 

 

c. (0.255 mol/L) * 1.50 L = 0.3825 mol

(0.800 mol/L) * 1.50 L = 1.20 mol

1.20 mol - 0.3825 mol = 0.8175 mol = 0.82 mol

K2SO4의 몰질량 = 174.26 g/mol

0.82 mol * (174.26 g/mol) = 142.8932 g = 143 g

( 계산 설명 http://ywpop.tistory.com/7738 )

 

 

d. MV = M’V’ ( 묽힘법칙 설명 http://ywpop.tistory.com/2859 )

(0.255 M) (40.0 mL) = (? M) (135 mL)

? = (0.255) (40.0) / (135) = 0.075555 = 0.0756 M

 

 

답: a. 0.00638 mol, b. 235 mL, c. 143 g, d. 0.0756 M

 

 

[ 관련 예제 http://ywpop.tistory.com/8758 ]