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2 years ago

A solution containing 292 g of Mg(NO3)2 per liter has a density of 1.108 g/mL. The molality of the solution is:

Chemistry

1 answer:

serg [7]2 years ago

6 0

Answer: D) 2.41 m

Explanation:

Molality of a solution is defined as the number of moles of solute dissolved per kg of the solvent.

$Molality=\frac{n}{W_s}$

where,

n = moles of solute

$W_s$ = weight of solvent in kg

moles of solute = $\frac{\text {given mass}}{\text {molar mass}}=\frac{292g}{148g/mol}=1.97moles$

volume of solution = 1L = 1000 ml (1L=1000ml)

Mass of solution= ${\text {Density of solution}}\times {\text {Volume of solution}}=1.108g/ml\times 1000ml=1108g$

mass of solute = 292 g

mass of solvent = mass of solution - mass of solute = (1108- 292) g = 816g = 0.816 kg

Now put all the given values in the formula of molality, we get

$Molality=\frac{1.97moles}{0.816kg}=2.41mole/kg$

Therefore, the molality of solution will be 2.41 mole/kg

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When C2H5Cl(g) is burned in oxygen, chlorine gas is produced in addition to carbon dioxide and water vapor. 5145 kJ of heat are

Arisa [49]

<u>Answer:</u> The chemical equation is written below.

<u>Explanation:</u>

Combustion reaction is defined as the chemical reaction in which a hydrocarbon reacts with oxygen gas to produce carbon dioxide gas and water molecule.

$\text{hydrocarbon}+O_2\rightarrow CO_2+H_2O$

The chemical equation for the combustion of ethyl chloride follows:

$4C_2H_5Cl+13O_2\rightarrow 2Cl_2+8CO_2+10H_2O$

We are given:

When 4 moles of ethyl chloride is burnt, 5145 kJ of heat is released.

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$A+\text{heat}\rightleftharpoons B$

For an exothermic reaction, heat is getting released during a chemical reaction and is written on the product side

$A\rightleftharpoons B+\text{heat}$

So, the chemical equation follows:

$4C_2H_5Cl+13O_2\rightarrow 2Cl_2+8CO_2+10H_2O+5145kJ$

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7 0

2 years ago

A 250. ml sample of 0.0328m hcl is partially neutralized by the addition of 100. ml of 0.0245m naoh. find the concentration of h

Ksenya-84 [330]

Answer: 0.0164 molar concentration of hydrochloric acid in the resulting solution.

Explanation:

1) Molarity of 0.250 L HCl solution : 0.0328 M

$Molarity=\frac{\text{Number of moles}}{\text{Volume of solution in liters}}=0.0328=\frac{\text{Number of moles}}{0.250 L}$

Moles of HCl in 0.250 L solution = 0.0082 moles

2) Molarity of 0.100 L NaOH solution : 0.0245 M

$Molarity=\frac{\text{Number of moles}}{\text{Volume of solution in liters}}=0.0245=\frac{\text{Number of moles}}{0.100 L}$

Moles of NaOH in 0.100 L solution = 0.00245 moles

3) Concentration of hydrochloric acid in the resulting solution.

0.00245 moles of NaOH will neutralize 0.00245 moles of HCl out of 0.0082 moles of HCl.

Now the new volume of the solution = 0.100 L +0.250 L = 0.350 L

Moles of HCl left un-neutralized = 0.0082 moles - 0.00245 moles = 0.00575 moles

$Molarity=\frac{\text{number of moles}}{\text{volume of solution in L}}$

Molarity of HCl left un-neutralized : $\frac{0.00575 moles}{0.350L}=0.0164 M$

0.0164 molar concentration of hydrochloric acid in the resulting solution.

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