Chemistry, 29.01.2020 23:55, mecennabosaaen

If you weigh out a piece of mg to a mass of 0.0240 g what is the minimum volume of 1.00 m hcl needed to ensure that the mg is the limiting reactant?

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answered: lllleklfkhlsdf1201

1.97 ml.

Explanation

Mg reacts with HCl at a 1:2 ratio.

Mg + 2 HCl → MgCl₂ + H₂.

How many moles of atoms in 0.0240 g of Mg?

The molar mass of Mg is 24.305 g/mol. In other words, the mass of one mole of Mg atoms is 24.305 gram.

$n = \dfrac{m}{M} = \dfrac{0.0240}{24.305} = 9.87 \times 10^{-4} \; \text{mol}$ .

How many moles of HCl does it take to oxidize that $9.87 \times 10^{-4} \; \text{mol}$ of Mg?

It takes 2 moles of HCl to oxidize 1 mole of Mg. As a result, it takes $2 \times 9.87 \times 10^{-4} = 1.97 \times 10^{-3}\; \text{mol}$ to oxidize $9.87 \times 10^{-4}\; \text{mol}$ of Mg.

Mg is the limiting reactant, meaning that HCl is in excess. There needs to be more than $1.97 \times 10^{-3}\; \text{mol}$ HCl for Mg to be the limiting reactant.

How many liters of 1.00 M HCl?

1.00 M is the same as 1.00 moles per liter.

$V = \dfrac{n}{c} = \dfrac{1.97 \times 10^{-3} \; \text{mol}}{1.00 \; \text{mol}\cdot \text{L}^{-1}} = 1.97 \times 10^{-3} \; \text{L} = 1.97 \; \text{mL}$ .

answered: Guest

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

answered: Guest

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noun

the practice of taking someone else's work or ideas and passing them off as one's own.

explanation:

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If you weigh out a piece of mg to a mass of 0.0240 g what is the minimum volume of 1.00 m hcl needed...