Chemistry

1. Which of the following statements are correct?
1. Most salts of carbonate ion are insoluble in water.
2. Most salts of chloride ion are soluble in water.
3. All salts of hydroxide ion are soluble in water.

1. is correct.
Among common salts of carbonate ion, all are insoluble except that Na2CO3,K2CO3 and (NH4)2CO3 aresoluble.

2. is correct.
Among common salts of chloride ion, all are soluble except that PbCl2­,AgCl, HgCl2­ and Hg2Cl2 are insoluble.

3. in incorrect.
Most of ionic compounds of hydroxide ion are insoluble.


2. Write the net ionic equation for the reaction ofaqueous sodium carbonate with aqueous aluminum chloride?

2Al^3+(aq) + 3CO3^2-(aq)→ Al2(CO3)3(s)


3. What are the spectator ions in the reactionbetween aqueous perchloric acid and aqueous sodium hydroxide?

Full equation: HClO4(aq) + NaOH(aq) → H2O(l) + NaClO4(aq)
Ionic equation: H^+(aq) + OH^-(aq) → H2O(l)

Spectator ions : sodium ion (Na^+) and perchlorate ion (ClO4^-)


4. What is the mole fraction of MgCl2 ina solution that is 5.52% by mass MgCl2(aq)? The molar mass of MgCl2is 95.21 g/mol.

In100 g of the solution:
No. of moles of MgCl2 = 100 x 5.52% / 95.21 = 0.05798 mol
No. of moles of H2O = 100 x (1 - 5.52%) / (1.008x2 + 16.00) =5.2442 mol

Mole fraction of MgCl2 = 0.05798/(0.05798 + 5.2442) = 0.01094


5. When 10.0 g of an unknown metal at 98.0 °C isplaced in 100. g H2O at 21.0 °C, the final temperature of the water is 24.0 °C.What is the specific heat capacity of the metal? The specific heat capacity ofwater is 4.184 J/g·K.

Letc = Specific heat capacity of the metal

Heat released by the metal = Heat absorbed by water
10.0 x c x (98.0 - 24.0) = 100 x 4.184 x (24.0 - 21.0)
Specific heat capacity of the metal, c = 1.696 J/g•K