bromide ion의 몰농도. What mass of BaBr2

bromide ion의 몰농도. What mass of BaBr2

 

 

a. What mass of BaBr2 must be added to 1.00*10^2 mL of 0.105 M HBr so that the resulting solution has a molarity of 0.150 M in Br^-? Assume the volume remains the same.

 

b. If 2.00*10^2 mL of water is added to the 0.150 M solution of bromide ion, what is the final molarity of bromide ion in the solution?

 

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a.

(0.105 mol/L) * 0.100 L = 0.0105 mol Br^-

(0.150 mol/L) * 0.100 L = 0.0150 mol Br^-

 

추가해야 될 Br^-의 양

0.0150 – 0.0105 = 0.0045 mol Br^-

 

BaBr2 → Ba^2+ + 2Br^-

0.0045 / 2 = 0.00225 mol BaBr2

 

BaBr2의 몰질량 = 297.14 g/mol

 

0.00225 mol * (297.14 g/mol) = 0.6686 g BaBr2

= 0.669 g BaBr2

 

 

b.

1.00*10^2 mL + 2.00*10^2 mL = 3.00*10^2 mL

 

0.0150 mol / 0.300 L = 0.0500 M