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3 years ago

Which of the following is a physical change. A piece of magnesium metal formed bubbles when dropped in acid

1 answer:

3 0

H2O became a vapor when heated because thats the only one that can go back to its normal state, which is what a physical change is.

You might be interested in

The valence electrons occur in what part of the atom?

shutvik [7]

The correct answer to the question that is stated above is letter c, the outer electron shell.

Valence electrons occur in the outermost shells of an atom.

>> Valence electrons are electrons that are associated with an atom, and that can participate in the formation of a chemical bond.

7 0

3 years ago

Read 2 more answers

En un recipiente colocamos unos cubos de hielo luego tapamos y observamos que sucede despues de un tiempo

SSSSS [86.1K]

Three questions come along with the given statement. It is in Spanish language:

a) Por qué se humedeció la parte exterior del frasco?

b) Por qué el hielo disminuyó su volumen y ahora es agua?

c) Por qué puede haber agua en el exterior?

These are the three answers (in English).

First question:

a) Por qué se humedeció la parte exterior del frasco?

The question is Why did the outside of the bottle get wet?

Answer:

The outside of the bottle get wet because the ice cubes cooled the walls of the bottle, so the air surrounding the bottle also cooled.

The air contains humidity (water) in gas phase. The hotter the air the more the amount of humidity it can retain, the cooler the air the less the amount of humidity it can retain.

Then, when the air close to the walls of the bootle got cooler some of the water in the air became liquid and those are the drops of water that you see in the outside of the bottle.

Second question

b) Por qué el hielo disminuyó su volumen y ahora es agua?

The question is Why did the ice diminish its volume and now it is water?

Answer:

The ice diminished its volume and now it is water, becasue the ice, which is cooler than the surroundings, received heat energy (from the surroundings) and then its temperature increased. At some moment, this temperature reached the melting point of the ice (water) and it started to become liquid.

Third question

c) Por qué puede haber agua en el exterior?

The question is: Why can there be water outside?

Answer:

The water outside is outside since the beginning: it is in the air. You do not see it because it is gas state. When the air close to the walss of the bottle got cooler, part of the water in the air became liquid.

4 0

3 years ago

the vapor pressure of a naqueous solution is found to be 24.9 mmgh at 25C. what is the mole fraction of solute in this solution?

Gekata [30.6K]

Answer:

Mole fraction of solute is 0.0462

Explanation:

To solve this we use the colligative property of lowering vapor pressure.

First of all, we search for vapor pressure of pure water at 25°C = 23.8 Torr

Now, we convert the Torr to mmHg. Ratio is 1:1, so 23.8 Torr is 23.8 mmHg.

Formula for lowering vapor pressure is:

ΔP = P° . Xm

Where ΔP = P' (Vapor pressure of solution) - P° (Vapor pressure of pure solvent)

Xm = mole fraction

24.9 mmHg - 23.8 mmHg = 23mmHg . Xm

Xm = (24.9 mmHg - 23.8 mmHg) / 23mmHg

Xm = 0.0462

8 0

3 years ago

How many single covalent bonds can halogens form?

Simora [160]

One single covalent bond, hope this helps!

4 0

3 years ago

How is it that when a salt sample dissolves in water, the delta S for the process is positive?

Bess [88]

Answer:-

Water is highly ordered. In water each oxygen atom is connected to others around it through hydrogen bonding via bridging hydrogen atoms. When a salt like NaCl is dissolved, some of these Hydrogen bonds break.

When a salt like NaCl dissolves in water, the NaCl breaks in to ions Na+ and Cl-.

The water molecules now surround these ions.

The slightly negative oxygen end of water molecule gets near the Na+, while the slightly positive Hydrogen of water molecule gets near the Cl-.

So before salt sample dissolve, the water molecules were highly ordered due to hydrogen bonding. Now after salt dissolve there is a decrease in order and thus an increase in disorder of the water molecules.

Due to increase in disorder, entropy which is a measure of disorder increases. Since entropy increases, delta S for the process is positive.

4 0

3 years ago