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3 years ago

During a phase change, such as melting or boiling, the kinetic energy __. Highlight correct answer

Chemistry

1 answer:

Pepsi [2]3 years ago

4 0

Answer: During a phase change, such as melting or boiling, the kinetic energy increases.

Explanation:

Kinetic energy is the energy obtained by the molecules of a substance due to their motion.

When phase change such as melting or boiling takes place then it means heat is absorbed by the substance. As a result, their molecules more even more rapidly from one place to another due to which more number of collisions take place.

Hence, a change in phase of substance occurs as kinetic energy increases in melting or boiling process.

Thus, we can conclude that during a phase change, such as melting or boiling, the kinetic energy increases.

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A sucrose solution is prepared to a final concentration of 0.250 M . Convert this value into terms of g/L, molality, and mass %.

MArishka [77]

Answer:

A. 85.6 g

= 0.0856 kg.

B. 0.00027 mol/g

= 0.27 mol/kg.

C. 8.39 %

Explanation:

Given:

Molar concentration = 0.25 M

Molar weight of sucrose = 342.296 g/mol

Density of solution = 1.02 g/mL

Mass of water = 934.4 g.

Density in g/l = 1.020 g/ml * 1000ml/1 l

= 1020 g/l

Mass of solution in 1 l of solution = 1020 g

Mass of solution = mass of solvent + mass of solute

Mass of sucrose = 1020 - 934.4

= 85.6 g of sucrose in 1 l of solution.

Density of sucrose = mass/volume

= molar mass/molar concentration

= 342.296 * 0.25

= 85.6 g/l

Number of moles = mass/molar mass

= 85.6/342.296

= 0.25 mol

Molality = number of moles of solute/mass of solvent

= 0.25/934.4

= 0.00027 mol/g

% mass of sucrose = mass of sucrose/total mass of solution * 100

= 85.6/1020 * 100

= 8.39 %

6 0

3 years ago

Lead forms two compounds with oxygen. One contains 2.98g of lead and 0.461g of oxygen. The other contains 9.89g of lead and 0.76

aliina [53]

The given question is incomplete, the complete question is:

Lead forms two compounds with oxygen. One contains 2.98g of lead and 0.461g of oxygen. The other contains 9.89g of lead and 0.763g of oxygen. For a given mass of oxygen, what is the lowest whole-number mass ratio of lead in the two compounds that combines with a given mass of oxygen?

Answer:

The lowest whole-number mass ratio in the two compounds is 1:2.

Explanation:

There is a need to find the mole ratio between lead and oxygen atoms in order to find the whole-number mass ratio of lead in the two compounds. In the first compound, the given mass of lead is 2.98 grams, the molar mass of lead is 207.2 gram per mole.

The no. of moles can be determined by using the formula,

moles = mass/molecular mass

moles = 2.98 g/207.2 g/mol

= 0.0144 moles

The mass of oxygen in the compound I is 0.461 grams, the molecular mass of oxygen is 16 gram per mol.

moles = 0.461 g /16 g/mol

= 0.0288 moles

The ratio between the lead and oxygen in the compound I is 0.0144/0.0288 = 1:2

On the other hand, in the compound II, the mass of lead given is 9.89 grams, therefore, the moles of lead in compound II is,

moles = 9.89 g / 207.2 g/mol

= 0.0477 moles

The mass of oxygen given in compound II is 0.763 grams, the moles of oxygen present in the compound II is,

moles = 0.763 g / 16 g

= 0.0477 moles

The ratio between the lead and oxygen in the compound II is, 0.0477 moles lead /0.0477 moles oxygen = 1:1

Hence, of the two compounds, the lowest ratio is found in the compound I, that is, 1:2.

4 0

3 years ago

A 93-L sample of dry air is cooled from 145 oC to -22 oC at a constant pressure of 2.85 atmospheres). What is the final volume?

Aloiza [94]

Answer: 55.84L

Explanation: Please see attachment for explanation.

3 0

3 years ago

Which do you think will cool down faster in? The teaspoon of water or the cup of water? Why?

777dan777 [17]

Answer:

I think the teaspoon will cool down faster.

Explanation:

The teaspoon of water will cool down faster because it is a smaller amount of water so the entire [drop] will absorb heat energy faster.

8 0

3 years ago

How does plastic impact the environment as a result of human activities

tresset_1 [31]

Answer:

As a result of human activities, plastic impacts the envionment in negative way that leads to serious environmental danger.

Explanation:

When we don't throw away plastic materials correctly, it causes littering. Well, this can also lead to piles of that, meaning that it is spreading toxins. Littering may also lead to blockages in flowing streams, lakes, river, ground water, big bodies of water, and small bodies of water. This also can contribute to global warming because plastic are made from chemicals that come from the production of fuels like oil, gas, coal and possible more.

7 0

3 years ago