All categories

2 years ago

If 0.25 moles of KBr is dissolved in 0.5 liters of

Chemistry

1 answer:

Len [333]2 years ago

6 0

Answer:

[KBr] = 454.5 m

Explanation:

m is a sort of concentration that indicates the moles of solute which are contianed in 1kg of solvent.

In this case, the moles of solute are 0.25 moles.

Let's determine the mass of solvent in kg.

Density of heavy water, solvent, is 1.1 g/L and our volume is 0.5L.

1.1 g = mass of solvent / 0.5L, according to density.

mass of solvent = 0.5L . 1.1g/L = 0.55 g

We convert the mass to kg → 0.55 g . 1kg /1000g = 5.5×10⁻⁴ kg

m = mol/kg → 0.25 mol /5.5×10⁻⁴ kg = 454.5 m

You might be interested in

Find the mass of 0.456 mol of Ca(OH)2 Please if you can show the work.

m_a_m_a [10]

Answer:

Ca(OH)2 molecular weight. Molar mass of Ca(OH)2 = 74.09268 g/mol. This compound is also known as Calcium Hydroxide. Convert grams Ca(OH)2 to moles or moles Ca(OH)2 to grams. Molecular weight calculation: 40.078 + (15.9994 + 1.00794)*2 ››

3 0

3 years ago

Read 2 more answers

The osmotic pressure of a solution containing 2.04 g of an unknown compound dissolved in 175.0 mLof solution at 25 ∘C is 2.13 at

kherson [118]

Answer: The molecular formula of the compound is $C_4H_{10}O_4$

Explanation:

To calculate the concentration of solute, we use the equation for osmotic pressure, which is:

$\pi=iMRT$

Or,

$\pi=i\times \frac{\text{Mass of solute}\times 1000}{\text{Molar mass of solute}\times \text{Volume of solution (in mL)}}\times RT$

where,

$\pi$ = osmotic pressure of the solution = 2.13 atm

i = Van't hoff factor = 1 (for non-electrolytes)

Given mass of compound = 2.04 g

Volume of solution = 175.0 mL

R = Gas constant = $0.0821\text{ L atm }mol^{-1}K^{-1}$

T = temperature of the solution = $25^oC=[273+25]=298K$

Putting values in above equation, we get:

$2.13atm=1\times \frac{2.04\times 1000}{\text{Molar mass of compound}\times 175.0}\times 0.0821\text{ L.atm }mol^{-1}K^{-1}\times 298K\\\\\text{Molar mass of compound}=\frac{1\times 2.04\times 1000\times 0.0821\times 298}{2.13\times 175.0}=133.9g/mol$

Calculating the molecular formula:

The chemical equation for the combustion of compound having carbon, hydrogen and oxygen follows:

$C_xH_yO_z+O_2\rightarrow CO_2+H_2O$

where, 'x', 'y' and 'z' are the subscripts of carbon, hydrogen and oxygen respectively.

We are given:

Mass of $CO_2=36.26g$

Mass of $H_2O=14.85g$

We know that:

Molar mass of carbon dioxide = 44 g/mol

Molar mass of water = 18 g/mol

For calculating the mass of carbon:

In 44 g of carbon dioxide, 12 g of carbon is contained.

So, in 36.26 g of carbon dioxide, $\frac{12}{44}\times 36.26=9.89g$ of carbon will be contained.

For calculating the mass of hydrogen:

In 18 g of water, 2 g of hydrogen is contained.

So, in 14.85 g of water, $\frac{2}{18}\times 14.85=1.65g$ of hydrogen will be contained.

Mass of oxygen in the compound = (22.08) - (9.89 + 1.65) = 10.54 g

To formulate the empirical formula, we need to follow some steps:

Step 1: Converting the given masses into moles.

Moles of Carbon = $\frac{\text{Given mass of Carbon}}{\text{Molar mass of Carbon}}=\frac{9.89g}{12g/mole}=0.824moles$

Moles of Hydrogen = $\frac{\text{Given mass of Hydrogen}}{\text{Molar mass of Hydrogen}}=\frac{1.65g}{1g/mole}=1.65moles$

Moles of Oxygen = $\frac{\text{Given mass of oxygen}}{\text{Molar mass of oxygen}}=\frac{10.54g}{16g/mole}=0.659moles$

Step 2: Calculating the mole ratio of the given elements.

For the mole ratio, we divide each value of the moles by the smallest number of moles calculated which is 0.659 moles.

For Carbon = $\frac{0.824}{0.659}=1.25\approx 1$

For Hydrogen = $\frac{1.65}{0.659}=2.5$

For Oxygen = $\frac{0.659}{0.659}=1$

Converting the mole fraction into whole number by multiplying the mole fraction by '2'

Mole fraction of carbon = (1 × 2) = 2

Mole fraction of oxygen = (2.5 × 2) = 5

Mole fraction of hydrogen = (1 × 2) = 2

Step 3: Taking the mole ratio as their subscripts.

The ratio of C : H : O = 2 : 5 : 2

The empirical formula for the given compound is $C_2H_5O_2$

For determining the molecular formula, we need to determine the valency which is multiplied by each element to get the molecular formula.

The equation used to calculate the valency is:

$n=\frac{\text{Molecular mass}}{\text{Empirical mass}}$

We are given:

Mass of molecular formula = 133.9 g/mol

Mass of empirical formula = 61 g/mol

Putting values in above equation, we get:

$n=\frac{133.9g/mol}{61g/mol}=2$

Multiplying this valency by the subscript of every element of empirical formula, we get:

$C_{(2\times 2)}H_{(5\times 2)}O_{(2\times 2)}=C_4H_{10}O_4$

Hence, the molecular formula of the compound is $C_4H_{10}O_4$

4 0

3 years ago

Which chemical element has the shortest name?

larisa86 [58]

Tin would be the right answer

5 0

3 years ago

Read 2 more answers

What changes chemical energy to something you can use

lutik1710 [3]

based on the law of conservation of energy its it atoms hold by strong chemical bonds

6 0

3 years ago

Describe the kinetic, potential and thermal energy of each state of matter?

Lerok [7]

Answer:

Particles of matter possess energy called kinetic energy.

Solid cannot be compressed, but gases are highly compressible.

The Kinetic energy of molecules of gases is very large & solids the least.

On heating a sublimable liquid, the molecules break free & escape from the surface of the solid directly into vapour.

Particles of matter move more rapidly on the application of heat

6 0

3 years ago