All categories

3 years ago

What is the mole fraction of water in 200g of 95 ethanol?

1 answer:

7 0

<span> If the solution is 95% by weight, that means that in 100 grams of solution you have 5 grams of water and 95 grams of ethanol.

Convert each of these masses to moles by dividing each mass by the molar mass of the compound.

5 g/18 g/mol = 0.278 mol water
95 g / 46g/mol = 2.065 mol ethanol

Mole fraction water:
= mol water / total moles
= 0.278/ (0.278 + 2.065)
= 0.119 </span>

You might be interested in

The pressure on a 200-milliliter sample of CO2(g) at

motikmotik

Answer:

A) 100 mL

Explanation:

At constant temperature and number of moles, Using Boyle's law

${P_1}\times {V_1}={P_2}\times {V_2}$

Given ,

V₁ = 200 mL

V₂ = ?

P₁ = 60 kPa

P₂ = 120 kPa

Using above equation as:

${P_1}\times {V_1}={P_2}\times {V_2}$

${60\ kPa}\times {200\ mL}={120\ kPa}\times {V_2}$

${V_2}=\frac{{60}\times {200}}{120}\ mL$

${V_2}=100\ mL$

3 0

3 years ago

How many molecules are in 145.5 grams of Be(OH)2

Zanzabum

Answer:

2.04 x 10²⁴ molecules

Explanation:

Given parameters:

Mass of Be(OH)₂ = 145.5g

To calculate the number of molecules in this mass of Be(OH)₂ we follow the following steps:

>> Calculate the number of moles first using the formula below:

Number of moles = mass/molarmass

Since we have been given the mass, let us derive the molar mass of Be(OH)₂

Atomic mass of Be = 9g

O = 16g

H = 1g

Molar Mass = 9 + 2(16 + 1)

= 9 + 34

= 43g/mol

Number of moles = 145.5/43 = 3.38mol

>>> We know that a mole is the amount of substance that contains Avogadro’s number of particles. The particles can be atoms, molecules, particles etc. Therefore we use the expression below to determine the number of molecules in 3.38mol of Be(OH)₂:

Number of

molecules= number of moles x 6.02 x 10²³

Number of molecules= 3.38 x 6.02 x 10²³

= 20.37 x 10²³ molecules

= 2.04 x 10²⁴ molecules

3 0

3 years ago

A gas occupies a volume of 180 mL at 35oC and 740 mmHg. What is the volume of the gas at STP?

Tasya [4]

Answer:

there you go

Explanation:

6 0

3 years ago

How many moles of oxygen must be placed

Annette [7]

0.24 moles of oxygen must be placed in a 3.00 L container to exert a pressure of 2.00 atm at 25.0°C.

The variables given are Pressure, volume and temperature.

Explanation:

Given:

P = 2 atm

V = 3 litres

T = 25 degrees or 298.15 K by using the formula 25 + 273.17 = K

R = 0.082057 L atm/ mole K

n (number of moles) = ?

The equation used is of Ideal Gas law:

PV = nRT

n = $\frac{PV}{RT}$

Putting the values given for oxygen gas in the Ideal gas equation, we get

n = $\frac{2 x 3}{0.082157 x 298.15}$

= 0.24

Thus, from the calculation using Ideal Gas law it is found that 0.24 moles of oxygen must be placed in a container.

Ideal gas law equation is used as it tells the relation between temperature, pressure and volume of the gas.

3 0

3 years ago

Read 2 more answers

Two or more different atoms are combined in definite proportions in any.

Stels [109]

<span>That would be compound!
Compounds are pure substances, which consists of two or more elements chemically combined in a fixed proportion by mass. Compounds have definite proportion.</span>

3 0

3 years ago