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frez [133]
2 years ago
9

41. A 13.0% solution of K2CO3 by mass has a density of 1.09 g/cm3. Calculate the molality of the solution.

Chemistry
1 answer:
PIT_PIT [208]2 years ago
5 0

Answer:

1.08 m is the molality of the solution.

Explanation:

1st step: Determine the mass of solvent.

13% by mass means that 13 g are contained in 100 g of solution.

Solution mass = Solute mass + solvent mass

100 g = 13 g + Solvent mass

Solvent mass = 100 g - 13 g → 87 g

Second Step: Let's determine the moles of our solute mass (mass / molar mass)

13 g / 138.2 g/mol = 0.094 moles

Third step: Replace the data to determine molality.

Molality are the moles of solute in 1kg of solvent (mol/kg)

Before this, we must convert the solvent mass to kg

87 g . 1kg / 1000 g = 0.087 kg

molality → 0.094 mol / 0.087 kg = 1.08 m

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Which statement is true about molarity and percent by mass?
Triss [41]

Answer : The correct option is, They are different units of concentration.

Explanation :

Molarity : It is defined as the number of moles of solute present in one liter of solution.

Formula of molarity :

\text{Molarity}=\frac{\text{Moles of solute}}{\text{Volume of solution in liters}}

Mass percent : It is defined as the mass of solute present in the mass of solution.

Formula of mass percent :

\text{Mass percent}=\frac{\text{Mass of solute}}{\text{Mass of solution}}\times 100

Hence, both are the different unit of concentration.

5 0
2 years ago
Read 2 more answers
What type of orbitals overlap to provide stability to the tert-butyl carbocation by hyperconjugation
larisa86 [58]

Explanation:

The - 3 degree C( carbon atom) 2p atomic orbital + methyl C-H sigma molecular orbital because one C-H bond has to dissolve its bond and provide the H that is sigma molecular orbital and the carbonation is type 3 degree sp2 carbon.

Hyperconjugation is the stabilizing effect arising from the electrons ' engagement in a π-bond (usually C-H or C-C) with a neighboring empty or partly filled p-orbital or π-orbital to provide an expanded molecular orbital that enhances system stability.

7 0
2 years ago
HELP! Ethanol has a density of 0.8 g/cm3. a. What is the mass of 225 cm3 of ethanol? b. What is the volume of 75.0 g of ethanol?
IRINA_888 [86]

Answer:

The correct answers are:

a) 180 g

b) 93.7 cm³

Explanation:

The density of a substance is the mass of the substance per unit of volume. So, it is calculated as follows:

density= mass/volume

From the data provided in the problem:

density = 0.8 g/cm³

a) Given: volume= 225 cm³

mass= density x volume = 0.8 g/cm³ x 225 cm³ = 180 g

b) Given: mass= 75.0 g

volume = mass/density = 75.0 g/(0.8 g/cm³)= 93.75 cm³≅ 93.7 cm³

5 0
2 years ago
Be sure to answer all parts. Draw the structure of a compound of molecular formula C4H8O that has a signal in its 13C NMR spectr
GenaCL600 [577]

Answer:

The possible structures are ketone and aldehyde.

Explanation:

Number of double bonds of the given compound is calculated using the below formula.

N_{db}=N_{c}+1-\frac{N_{H}+N_{Br}-N_{N}}{2}

N_{db}=Number of double bonds

N_{c} = Number of carbon atoms

N_{H} = Number of hydrogen atoms

N_{N} = Number of nitrogen atoms

The number of double bonds in the given formula - C_{4}H_{8}O

N_{db}= 4+1-\frac{8+0-0}{2}=1

The number of double bonds in the compound is one.

Therefore, probable structures is as follows.

(In attachment)

The structures I and III are ruled out from the probable structures because the signal in 13C-NMR appears at greater than 160 ppm.

alkene compounds I and II shows signal less than 140 ppm.

Hence, the probable structures III and IV are given as follows.

The carbonyl of structure I appear at 202 and ketone group of IV appears at 208 in 13C, which are greater than 160.

Hence, the molecular formula of the compound C_{4}H_{8}O having possible structure in which the signal appears at greater than 160 ppm are shown aw follows.

8 0
2 years ago
explain how energy changes from one form to another in a exothermic reaction. in an endothermic reaction.
Alexxx [7]

Answer:

Exothermic reaction: In exothermic reaction, energy is transferred to the surroundings, and the surrounding temperature increases, this is known as exothermic reaction. In other words energy exits in exothermic reaction. Some example of exothermic reactions are:

1) Neutralisation reaction.

2) Combustion reaction.

3) Some oxidation reaction.

Endothermic reaction: In endothermic reaction, energy is taken in from the surrounding, and the surrounding temperature decreases, this is known as endothermic reaction. In other words energy enters in endothermic reaction. Some example of exothermic reactions are:

1) Thermal decomposition.

2) Reaction between citric acid and sodium hydrogen carbonate.

6 0
2 years ago
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