Write a molecular equation for the precipitation reaction that occurs (if any) when the following solutions are mixed. if no reaction occurs, write noreaction.
sodium chloride and lead (ii) acetate
potassium sulfate and strontium iodide
chromium (iii) nitrate and sodium phosphate

All the reactions are precipitation reactions.

Explanation:

Precipitation reaction is defined as the reaction in which an insoluble salt is formed when two solutions are mixed containing soluble substances. The insoluble salt settles down at the bottom of the reaction mixture.

For the given options:

Option 1: Sodium chloride and lead (II) acetate

The chemical equation follows:

As, lead (II) chloride is forming as a solid product. It is considered as a precipitation reaction.

Option 2: Potassium sulfate and strontium iodide

The chemical equation follows:

As, strontium sulfate is forming as a solid product. It is considered as a precipitation reaction.

Option 3: Chromium (III) nitrate and sodium phosphate

The chemical equation follows:

As, chromium (III) phosphate is forming as a solid product. It is considered as a precipitation reaction.

Hence, all the reactions are precipitation reactions.

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

answer: cellular respiration takes in food and uses it to create atp, a chemical which the cell uses for energy. usually, this process uses oxygen, and is called aerobic respiration. it has four stages known as glycolysis, link reaction, the krebs cycle, and the electron transport chain.