1. Will a precipitate form if solutions of potassium sulfate and barium nitrate are combined? If so, write the net ionic equation for the reaction.
2. Will a precipitate form if solutions of potassium nitrate and magnesium sulfate are combined? If so, write the net ionic equation for the reaction.
3. Will a precipitate form if solutions of barium chloride and sodium sulfate are combined? If so, identify the spectator ions and write the net ionic equation.
4. Write the net ionic equation for the precipitation of nickel(II) sulfide slader

Explanation:

1.

YES

K2SO4(aq) + Ba(NO3)2(aq) --> Ba(SO4)2(s) + 2KNO3(aq)

Net ionic equation

2SO4^2-(aq) + Ba2+(aq) --> Ba(SO4)2(s)

2.

NO

No precipitate is formed because KNO3, MgSO4, K2SO4 and Mg(NO3)2 all are soluble.

3.

YES

BaCl2(aq) + Na2(SO4)(aq) --> BaSO4(s) + 2NaCl(aq)

Net ionic equation:

Ba2+(aq) + SO4^2-(aq) --> BaSO4(aq)

4.

Ni2+(aq) + S2-(aq) ---> NiS(s)

part 1: the half-life of the element is 22 years.

part 2: it will take 132.02 year for the sample to decay from 308.0 g to 4.8125 g.

explanation:

part 1: there are two ways to determine the half life time.

first way: the half life time can be determined directly from its definition as it is the time required for the sample to decay to its half concentration.

from the data the initial concentration was 45.0 g and decayed to its half value (22.5 g) in 22.0 years.

second way: the radio active decay is considered first order reaction so we can use the laws of first order reactions.

k = (1/t) ln (a/a-x), where k is the rate constant of the reaction,

t is the time of the reaction

a is the initial concentration of the reactant

a-x is the remaining concentration at time (t)

a = 45.0 g the initial concentration at t = 0 year.

at t = 22 year, a-x = 22.5 g

then k = (1/22 year) ln (45.0 g/ 22.5 g) = 0.0315 year-1.

the half-life time (t1/2) = ln 2/ k = 0.693/ k =0.693/ 0.0315 = 22 years.

part 2:

using the same law k = (1/t) ln (a/a-x),

using the given data; a = 308.0 g and a-x = 4.8125 g and the calculated k from the part 1 (k = 0.0315 year-1)

t = (1/k) ln (a/a-x) = (1/0.0315) ln (308.0/ 4.8125) = 132.02 years

the answer is either b or c