Question

 8 Write the balanced NET ionic equation for the reaction when copper(II) sulfate and ammonium hydroxide are mixed in aqueous solution. If no reaction occurs, write only NR.

 9 In the reaction between FeCl3 and NaOH, the spectator ions are

 10 Convert the concentration of 0.700 M Na2SO4 to g/mL

 11 How many mililiters of water should a chemist add if they want to prepare an 0.200 M aqueous solution with 30.2 g of NaCI ? Assume the density of the resulting solution is the same as the water.

 12 What is the mass in grams of NaCN in 120.0 mL of a 2.40 x 10^-5 M solution?

Answer 1

8)

CuSO4(aq) + 2NH4OH(aq) ----> (NH4)2SO4(aq) + Cu(OH)2(s)

Cu2+(aq) + SO4 2-(aq) + 2NH4 +(aq) + 2OH-(aq) ----> 2NH4 +(aq) + SO4 2-(aq) + Cu(OH)2(s)

So, net ionic reaction;

Cu2+(aq) + 2OH-(aq) ----> Cu(OH)2(s)

9)

FeCl3(aq) + 3NaOH(aq) ----> Fe(OH)3(s) + 3NaCl(aq)

Fe3+(aq) + 3Cl-(aq) + 3Na+(aq) + 3OH-(aq) ---> Fe(OH)3(s) + 3Na+(aq) + 3Cl-(aq)

The ions which are in same phase on both side are spectator ions.

Hence, Cl- , Na+ ....Answer

10)

0.700 M means 0.700 moles of Na2SO4 in 1000 ml (1 liter) solution.

Mass of Na2SO4 = moles * molar mass = 0.700 * 142 = 99.4 grams

Thus, 0.700 M = 99.4/1000 g/ml = 0.0994 g/ml ...Answer

11)

Moles of NaCl = mass in grams/molar mass = 30.2/58.5 = 0.51624

Molarity = moles/volume in liters

0.200 = 0.51624 / V

V = 2.5812 liters = 2581.2 ml ....Answer

12)

1000 ml solution contains 2.40*10^-5 moles of NaCN

So, 120 ml solution will contain = (2.40*10^-5)*(120) / 1000 = 0.00000288 moles of NaCN

Mass of NaCN = moles * molar mass = 0.00000288 * 49 = 0.0001411 grams ...Answer