A solution is made by mixing of 51 g of heptane and of acetyl bromide . Calculate the mole fraction of heptane in this solution. Round your answer to significant digits.

The question is incomplete, here is the complete question:

A solution is made by mixing of 51 g of heptane and 127 g of acetyl bromide. Calculate the mole fraction of heptane in this solution. Round your answer to 3 significant digits.

The mole fraction of heptane in the solution is 0.330

Explanation:

To calculate the number of moles, we use the equation:

    .....(1)

Given mass of heptane = 51 g

Molar mass of heptane = 100.2 g/mol

Putting values in equation 1, we get:

Given mass of acetyl bromide = 127 g

Molar mass of acetyl bromide = 123 g/mol

Putting values in equation 1, we get:

Mole fraction of a substance is given by:

Moles of heptane = 0.509 moles

Total moles = [0.509 + 1.032] = 1.541 moles

Putting values in above equation, we get:

Hence, the mole fraction of heptane in the solution is 0.330

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; natural resources;