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igor_vitrenko [27]
2 years ago
5

To determine the freezing point depression of a LiCl solution, Toni adds 0.411 g of LiCl to the sample test tube along with 19.7

mL of distilled water. Determine the molal concentration (m) of the resulting solution. MWLiCl
Chemistry
1 answer:
Cerrena [4.2K]2 years ago
7 0

Answer:

LiCl = 0.492 m

Explanation:

Molal concentration is the one that indicates the moles of solute that are contained in 1kg of solvent.

Our solute is lithium chloride, LiCl.

Our solvent is distilled water.

We do not have the mass of water, but we know the volume, so we should apply density to determine mass.

Density = mass / volume

Density . volume = mass

1 g/mL . 19.7 mL = 19.7 g

We convert g to kg → 19.7 g . 1 kg / 1000g = 0.0197 kg

Let's determine the moles of LiCl

0.411 g . 1 mol / 42.394 g = 9.69×10⁻³ moles

Molal concentration (m) = 9.69×10⁻³ mol / 0.0197 kg → 0.492 m

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wlad13 [49]

Answer:

autotrophs

Explanation:

3 0
3 years ago
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What is the pressure inside a 2.0 L bottle filled with 0.25 mol of carbon dioxide gas at 25 °C?
motikmotik

Answer:

3.1atm

Explanation:

Given parameters:

Volume of gas = 2L

Number of moles  = 0.25mol

Temperature  = 25°C = 25 + 273  = 298K

Unknown:

Pressure of the gas = ?

Solution:

To solve this problem, we use the ideal gas equation.

This is given as;

       PV  = nRT

P is the pressure

V is the volume

n is the number of moles

R is the gas  constant  = 0.082atmdm³mol⁻¹K⁻¹

T is the temperature

          P  = \frac{nRT}{V}  

 Now insert the parameters and solve;

         P  = \frac{0.25 x 0.082 x 298}{2}   = 3.1atm

8 0
3 years ago
A reaction was performed in which 3.6 g 3.6 g of benzoic acid was reacted with excess methanol to make 1.3 g 1.3 g of methyl ben
Anit [1.1K]

<u>Answer:</u> The percent yield of the reaction is 32.34 %

<u>Explanation:</u>

To calculate the number of moles, we use the equation:

\text{Number of moles}=\frac{\text{Given mass}}{\text{Molar mass}}     .....(1)

  • <u>For benzoic acid:</u>

Given mass of benzoic acid = 3.6 g

Molar mass of benzoic acid = 122.12 g/mol

Putting values in equation 1, we get:

\text{Moles of benzoic acid}=\frac{3.6g}{122.12g/mol}=0.0295mol

The chemical equation for the reaction of benzoic acid and methanol is:

\text{Benzoic acid + methanol}\rightarrow \text{methyl benzoate}

By Stoichiometry of the reaction

1 mole of benzoic acid produces 1 mole of methyl benzoate

So, 0.0295 moles of benzoic acid will produce = \frac{1}{1}\times 0.0295=0.108 moles of methyl benzoate

  • Now, calculating the mass of methyl benzoate from equation 1, we get:

Molar mass of methyl benzoate = 136.15 g/mol

Moles of methyl benzoate = 0.0295 moles

Putting values in equation 1, we get:

0.0295mol=\frac{\text{Mass of methyl benzoate}}{136.15g/mol}\\\\\text{Mass of methyl benzoate}=(0.0295mol\times 136.15g/mol)=4.02g

  • To calculate the percentage yield of methyl benzoate, we use the equation:

\%\text{ yield}=\frac{\text{Experimental yield}}{\text{Theoretical yield}}\times 100

Experimental yield of methyl benzoate = 1.3 g

Theoretical yield of methyl benzoate = 4.02 g

Putting values in above equation, we get:

\%\text{ yield of methyl benzoate}=\frac{1.3g}{4.02g}\times 100\\\\\% \text{yield of methyl benzoate}=32.34\%

Hence, the percent yield of the reaction is 32.34 %

6 0
3 years ago
Which of the following is true for balancing equations?
nataly862011 [7]

Answer:

D) There must be equal number of atoms of each elements on both sides of equation.

Explanation:

The balancing equation must have equal number of atoms of each elements on both sides of equation.

The balance equation shoes mass is conserved thus followed the law of conservation of mas.

Law of conservation of mass:

According to the law of conservation mass, mass can neither be created nor destroyed in a chemical equation.

Explanation:

This law was given by french chemist  Antoine Lavoisier in 1789. According to this law mass of reactant and mass of product must be equal, because masses are not created or destroyed in a chemical reaction.

For example:

In given photosynthesis reaction:

6CO₂ + 6H₂O + energy → C₆H₁₂O₆ + 6O₂

there are six carbon atoms, eighteen oxygen atoms and twelve hydrogen atoms on the both side of equation so this reaction followed the law of conservation of mass.

8 0
3 years ago
What is the half-life in minutes of a compound if 75.0 percent of a given sample decomposes in 40.0 minutes? Assume first-order
yaroslaw [1]

Answer:

See below

Explanation:

.75 = 1/2^(40/h)      

log .75 / ( log 1/2) = 40 / h

<u>h = half life =   96.37683 min</u>

8 0
2 years ago
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