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3 years ago

1.20g of methyl alcohol, CH3OH, are dissolved in 16.8g of water, H2O. What is the mole fraction of the solute?

Chemistry

2 answers:

kolezko [41]3 years ago

7 0

Answer:

0.0386

Explanation:

To make a solution, we need a certain amount of the solute to be dissolved in the solvent. The solvent is the carrier medium usually water in traditional wet chemistry.

Now, in this particular question, it should be known that methyl alcohol is the solute, while water is the solvent.

We need to calculate the mole fraction of the solute as asked by the question. Now what we do is to find the number of moles of each, add together, then divide the number of moles of methyl alcohol by the sum of the moles of both.

Firstly, we calculate the number of moles of methyl alcohol present. This is mathematically equal to dividing mass by molar mass

Molar mass of methyl alcohol (CH3OH) is 12 + 4(1) + 16 = 32g/mol

The number of moles is thus 1.2/32 = 0.0375 moles

Now, we calculate the number of moles of water. The molar mass of water is 18g/mol

The number of moles of water is thus 16.8/18 = 0.93333

The mole fraction of the solute is thus:

0.0375/(0.0375 + 0.9333) = 0.0386

andreyandreev [35.5K]3 years ago

5 0

Answer:

The mole fraction of the solute, methyl alcohol, is 0.0387

Explanation:

Step 1: Data given

Mass of methyl alcohol = 1.20 grams

Molar mass of methyl alchol = 32.04 g/mol

Mass of water = 16.8 grams

Molar mass of water = 18.02 g/mol

Step 2: Calculate number of moles of methyl alcohol

Number of moles methyl alcohol = Mass / molar mass

Number of moles methyl alcohol = 1.20 grams / 32.04 grams

Number of moles methyl alcohol = 0.0375 moles

Step 3: Calculate number of moles of water

Moles H2O = 16.8 grams / 18.02 g/mol

Moles H20 = 0.932 moles

Step 4: Calculate total number of moles

Total number of moles = moles CH3OH + moles H2O = 0.0375 moles + 0.932 moles = 0.9695 moles

Step 5: Calculate mole fraction of the solute

Solute = methyl alchol

(Solvent = water)

Mole fraction = 0.0375 moles / 0.9695 moles

Mole fraction = 0.0387

The mole fraction of the solute, methyl alcohol, is 0.0387

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Natasha_Volkova [10]

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3 years ago

Given the following heats of combustion. CH3OH(l) + 3/2 O2(g) CO2(g) + 2 H2O(l) ΔH°rxn = -726.4 kJ C(graphite) + O2(g) CO2(g) ΔH

sergeinik [125]

Answer:

The standard enthalpy of formation of methanol is, -238.7 kJ/mole

Explanation:

The formation reaction of CH_3OH will be,

$C(s)+2H_2(g)+\frac{1}{2}O_2\rightarrow CH_3OH(g),\Delta H_{formation}=?$

The intermediate balanced chemical reaction will be,

$C(graphite)+O_2(g)\rightarrow CO_2(g), \Delta H_1=-393.5kJ/mole$ ..[1]

$H_2(g)+\frac{1}{2}O_2(g)\rightarrow H_2O(l), \Delta H_2=-285.8kJ/mole$ ..[2]

$CH_3OH(g)+\frac{3}{2}O_2(g)\rightarrow CO_2(g)+2H_2O(l) , \Delta H_3=-726.4kJ/mole$ ..[3]

Now we will reverse the reaction 3, multiply reaction 2 by 2 then adding all the equations, Using Hess's law:

We get :

$C(graphite)+O_2(g)\rightarrow CO_2(g) , \Delta H_1=-393.5kJ/mole$ ..[1]

$2H_2(g)+2O_2(g)\rightarrow 2H_2O(l) ,\Delta H_2=2\times (-285.8kJ/mole)=-571.6kJ/mol$ ..[2]

$CO_2(g)+2H_2O(l)\rightarrow CH_3OH(g)+\frac{3}{2}O_2(g) ,\Delta H_3=726.4kJ/mole$ [3]

The expression for enthalpy of formation of $C_2H_4$ will be,

$\Delta H_{formation}=\Delta H_1+2\times \Delta H_2+\Delta H_3$

$\Delta H=(-393.5kJ/mole)+(-571.6kJ/mole)+(726.4kJ/mole)$

$\Delta H=-238.7kJ/mole$

The standard enthalpy of formation of methanol is, -238.7 kJ/mole

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2 years ago

If 20 grams of Zinc phosphate reacts with excess hydrochloric acid and produces 18 grams of Zinc chloride what is the percent yi

fenix001 [56]

Answer:

$Y=85\%$

Explanation:

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In this case, since we know the balanced chemical reaction, we are first able to realize there is a 1:3 mole ratio between zinc phosphate and zinc chloride; it means that we can first compute the moles of the desired product via stoichiometry:

$n_{ZnCl_2}=20gZn_3(PO_4)_2*\frac{1molZn_3(PO_4)_2}{386.11gZn_3(PO_4)_2}*\frac{3molZnCl_2}{1molZn_3(PO_4)_2}=0.16gZnCl_2$

Next, since those moles are associated with the theoretical yield of zinc chloride, we obtain the corresponding mass:

$m_{ZnCl_2}^{theoretical}=0.16molZnCl_2*\frac{136.29gZnCl_2}{1molZnCl_2} =21gZnCl_2$

Finally, we compute the percent yield by diving the actual yield (18 g) by the theoretical yield:

$Y=\frac{18g}{21g}*100\%\\\\Y=85\%$

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2 years ago

He molecular formula mass of this compound is 180 amu . what are the subscripts in the actual molecular formula?

mezya [45]

I can't actually answer this one if the empirical formula is not given. Luckily, I've found a similar problem from another website. The problem is shown in the picture attached. It shows that the empirical formula is CH₂O. Let's calculate the molar mass of the empirical formula.

Molar mass of E.F = 12 + 2(1) + 16 = 30 g/mol

Then, let's divide this to the molar mass of the molecular formula.
Molar mass of M.F/Molar mass of E.F = 180/30 = 6

Therefore, let's multiply 6 to each subscript in the empirical formula to determine the actual molecular formula.
<em>Actual molecular formula = C₆H₁₂O₆</em>

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2 years ago

Find the area of a vegetable garden that is 4.83m long and 3.4m wide. Give your answer to the correct significant figure. (use t

sergejj [24]

Answer:

The area of vegetable garden is 16.422 m².

Explanation:

Given data:

Length = 4.83 m

Width = 3.4 m

Area = ?

Solution:

Formula:

Area = length × width

Area is measured in square unit.

By putting the values in formula:

Area = length × width

Area = 4.83 m × 3.4 m

Area = 16.422 m²

The area of vegetable garden is 16.422 m².

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3 years ago