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2 years ago

Calculate the mass in grams of NaCl required to prepare 0.500 L of a 0.500 M solution.

Chemistry

1 answer:

IceJOKER [234]2 years ago

7 0

Answer:

14.61 g NaCl

Explanation:

Molarity = moles / volume of solution (litres)

0.500 = moles / 0.500 L

moles = 0.25

Molar mass of NaCl is 58.44 g NaCl /1 mol NaCl.

0.25 moles NaCl x 58.44 g NaCl /1 mol NaCl

= 14.61 g NaCl

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in order to find the molar mass of an unknown compound, a research scientist prepared a solution of 0.930 g of an unknown in 125

PtichkaEL [24]

Answer:

Molar mass→ 0.930 g / 6.45×10⁻³ mol = 144.15 g/mol

Explanation:

Let's apply the formula for freezing point depression:

ΔT = Kf . m

ΔT = 74.2°C - 73.4°C → 0.8°C

Difference between the freezing T° of pure solvent and freezing T° of solution

Kf = Cryoscopic constant → 5.5°C/m

So, if we replace in the formula

ΔT = Kf . m → ΔT / Kf = m

0.8°C / 5.5 m/°C = m → 0.0516 mol/kg

These are the moles in 1 kg of solvent so let's find out the moles in our mass of solvent which is 0.125 kg

0.0516 mol/kg . 0.125 kg = 6.45×10⁻³ moles. Now we can determine the molar mass:

Molar mass (mol/kg) → 0.930 g / 6.45×10⁻³ mol = 144.15 g/mol

3 0

3 years ago

the heat of fusion of acetone is 5.7 kJ/mol. Calculate to two significant figures the entropy change when 6.3 mol of acetone mel

shtirl [24]

<u>Answer:</u> The entropy change of the process is $2.0\times 10^2J/K$

<u>Explanation:</u>

To calculate the entropy change for different phase at same temperature, we use the equation:

$\Delta S=n\times \frac{\Delta H_{f}}{T}$

where,

$\Delta S$ = Entropy change

n = moles of acetone = 6.3 moles

$\Delta H_{f}$ = enthalpy of fusion = 5.7 kJ/mol = 5700 J/mol (Conversion factor: 1 kJ = 1000 J)

T = temperature of the system = $-94.7^oC=[273-94.7]=178.3K$

Putting values in above equation, we get:

$\Delta S=\frac{6.3mol\times 5700J/mol}{178.3K}\\\\\Delta S=201.4J/K=2.0\times 10^2J/K$

Hence, the entropy change of the process is $2.0\times 10^2J/K$

4 0

3 years ago

What does a balanced equation allows you to determine

Allushta [10]

It allows you to determine the relation between the reactants and the products.

7 0

3 years ago

A glass column is filled with mercury and inverted in a pool of mercury. The mercury column stabilizes at a height of 729 mm abo

harkovskaia [24]

The atmospheric pressure will be:

The pressure of the atmosphere resulting from the mercury column is 0.959 atm

What is atmospheric pressure?

The force that an object experiences from the weight of the air above it per unit area are known as atmospheric pressure.

Given: Height of mercury column = 729 mm Hg

To find: The pressure of the atmosphere

Calculation:

The atmospheric column resulting from the mercury column is calculated as follows:

1 atm =760 mm Hg

So, we can convert the 729 mm Hg to atm, and we get

Atmospheric pressure = 729 x 1 atm / 760 = 0.959 atm

Learn more about atmospheric pressure here,

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5 0

1 year ago

A slice of Swiss cheese contains 48 mg of sodium

Nookie1986 [14]

Answer: grams=0.048g, ounces=0.0017oz, 0.00011lb

Explanation:

Stoichiometry

48 mg x 1 g

÷ 1000 mg = 0.048 g

48 mg x 1 g x 16 oz

÷ 1000 mg ÷ 453.6 g = 0.0017 oz

48 mg x 1 g x 1 lb

÷ 1000 mg ÷ 453.6 g = 0.00011 lb

6 0

3 years ago