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4 years ago

A solution of salt water is boiled. The water evaporates and solid salt remains. Which statement is true?

Chemistry

2 answers:

astraxan [27]4 years ago

8 0

Answer is: C. The salt and the water have both undergone physical changes.

The salt and the water make a homogeneous mixture (the same proportions of its components throughout any given sample).

A physical change occurs when a substance changes phase.

Boiling is a physical change (process), the same substance is present before and after the change, so chemical bonds and melting point of the substance are not changed.

Chemical change is when new substances are formed, the atoms are rearranged and the reaction is followed by an energy change.

kow [346]4 years ago

5 0

The answer would be C.

The salt and the water have both undergone physical changes.

Hope this helps!

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Which of the following changes in the state of a substance results in an increase in the entropy? Gas to solid Gas to liquid Liq

kifflom [539]

Answer:

Solid to liquid

Explanation:

Entropy is a state of randomness or disorderliness of the particles of a system. Some part of the heat energy of a system is related to the state of disorder or randomness of the particles of the system.

The entropic level of a system depends on two of major factors:

1. Temperature: Entropy increases with temperature rise due to the fact that the randomness of the particles of a system increases at a higher temperature.

2. Physical state of matter: The increasing order of entropy is:

Solid < Liquid < Gas

Gases are the most disordered and have the highest entropy. In moving from solid to liquid to gas, entropy of a system would increase.

8 0

3 years ago

15.0 g of cream at 16.4 °C are added to an insulated cup containing 100.0 g of coffee at 86.5 °C. Calculate the equilibrium temp

Marta_Voda [28]

115 grams total

15/115= 13%

109/115= 87%

.13x 16.4= .277

.87x 86.5= 75.255

75.255+.277= 75.532 deg C
or 75.5 as 3 significant digits

7 0

3 years ago

How many molecules of N2O4 are in 76.3g N2O4? The molar mass of N2O4 is 92.02 g/mol.

Murrr4er [49]

Answer:

4.99*10²³ molecules of N₂O₄ are in 76.3 g of N₂O₄

Explanation:

Avogadro's Number is the number of particles that make up a substance (usually atoms or molecules) and that can be found in the amount of one mole of said substance. Its value is 6.023*10²³ particles per mole. Avogadro's number represents a quantity without an associated physical dimension. Avogadro's number applies to any substance.

You know that the molar mass of N₂O₄ is 92.02 g/mol, and you have 76.3 g. Then you can apply the following rule of three: 92.02 grams are present in 1 mole of the compound, 76.3 grams in how many moles are they?

$amount of moles= \frac{76.3 grams*1 mole}{92.02 grams}$

amount of moles= 0.83 moles

Then, you can apply another rule of three: if by definition of Avogadro's number 1 mole of the compound has 6.023*10²³ molecules, 0.83 moles of the compound, how many molecules will it have?

$amount of molecules= \frac{0.83 moles*6.023*10^{23}molecules }{1 mole}$

amount of molecules= 4.99*10²³

<u><em>4.99*10²³ molecules of N₂O₄ are in 76.3 g of N₂O₄</em></u>

6 0

3 years ago

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ollegr [7]

The correct reference for this isotope is A. Oxygen-18.

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3 years ago

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matrenka [14]

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3 years ago

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