I need help with these homework problem sets as I have no clue how to engage int
ID: 1047863 • Letter: I
Question
I need help with these homework problem sets as I have no clue how to engage into them!
14. (5pnts) What is the molarity of potassium ion in the following solutions: a. 0.20 M potassium chloride b. 0.15 M potassium chromate c. 0.080 M potassium phosphate 15. (5pnts) How many mL of 6.0 M nitric acid are needed to prepare 100.0 mL of 0.500 M nitric acid? 16. (5pnts) Pure acetic acid, known as glacial acetic acid, is a liquid with a density of 1.049 g/mL. Calculate the molarity of a solution of acetic acid made by dissolving 20.00 mL of glacial acetic acid in enough water to make 250.0 mL of solution. 17. (5pnts) How many milliliters of 0.128 M hydrochloric acid is needed to neutralize 2.87 g of solid magnesium hydroxide? 18. (5pnts) If 25.8 mL of a silver nitrate solution is needed to precipitate all the chloride ions in a 785- mg sample of KCI (forming silver chloride), what is the molarity of the AgNO3 solution?Explanation / Answer
a. KCl ---------> K+ + Cl-
0.2M 0.2M
molarity of K+ is 0.2M
b. K2CrO4 --------> 2K+ + CrO42-
0.15M 2*0.15M
molarity of K+ is 0.3M
c. K3PO4 ----------> 3K+ + PO43-
0.08M 3*0.08M
molarity of K+ is 0.24M
15. initial Final
M1 = 6M M2 = 0.5M
V1 = V2 = 100ml
M1V1 = M2V2
V1 = M2V2/M1
= 0.5*100/6 = 8.33ml
16. mass of acetic acid = volume* density
= 20*1.049 = 20.98g
molarity = 20.98*1000/60*250 = 1.4M
17. no of moles of Mg(OH)2 = W/G.M.Wt
= 2.87/58.31 = 0.05moles
Mg(OH)2 + 2HCl ---------> MgCl2 +2H2O
1 mole of Mg(OH)2 react with 2 moles of HCl
0.05 moles of Mg(OH)2 react with = 2*0.05/1 = 0.1mole of HCl
molarity = no of moles/volume in L
0.128 = 0.1/volume in L
volume in L = 0.1/0.128 = 0.78L
= 780ml