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lara [203]
3 years ago
6

Energy increases heat and causes a phase change from solid to liquid or liquid to solid

Chemistry
1 answer:
weqwewe [10]3 years ago
7 0
<span>So, how could there be a change in heat during a state change without a change in temperature? During a change in state the heat energy is used to change the bonding between the molecules. In the case of melting, added energy is used to break the bonds between the molecules. In the case of freezing, energy is subtracted as the molecules bond to one another. These energy exchanges are not changes in kinetic energy. They are changes in bonding energy between the molecules.If heat is coming into a substance during a phase change, then this energy is used to break the bonds between the molecules of the substance. The example we will use here is ice melting into water. Immediately after the molecular bonds in the ice are broken the molecules are moving (vibrating) at the same average speed as before, so their average kinetic energy remains the same, and, thus, their Kelvin temperature remains the same.</span>

 

Below is a picture of solid ice melting into liquid water. The molecule of ice and the molecule of water (the black balls) are moving with the same rate of vibration in this diagram. This is meant to show that they have the same average speed and thus the same average kinetic energy (since they have the same mass) and thus the same Kelvin temperature. The motions are, though, greatly exaggerated. Actually, the motions of the molecules should be considered tiny vibrations.

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A container of oxygen has a volume of 30.0 mL and a pressure of 72.5 psi. If the pressure of the oxygen gas is reduced to 28 psi
OLga [1]

Answer:

THE NEW VOLUME OF THE OXYGEN GAS AT 28 PSI FROM 72.5 PSI IS 0.078 L.

Explanation:

Initial volume of the oxygen in the container = 30.0 mL = 30 / 000 L = 0.03 L

Initial pressure of the oxygen = 72.5 psi =  1 psi = 6890 pascal

Final pressure = 28 psi

Final volume = unknown

First convert the mL to L and since both pressures are in similar unit that is psi; there is no need converting them to pascal or other standard unit of pressure. They cancel each other out.

This question follows Boyle's equation of gas laws and mathematically it is written as:

P1 V1 = P2 V2

Re-arranging by making P2 the subject of the formula, we have:

V2 = P1 V1 / P2

V2 = 72,5 * 0.03 / 28

V2 = 2.175 /28

V2 = 0.0776 L

The new volume of the oxygen gas at a change in pressure from 72.5 psi to 28 psi is 0.078 L.

8 0
3 years ago
The air temperature surrounding a snowy driveway is 0ºC. One side of the driveway is shaded, while the other side is sunny. The
ICE Princess25 [194]

Answer:

The snow absorbed radiant energy to produce a physical change.

Explanation:

8 0
3 years ago
2 HI(g) ⇄ H2(g) + I2(g) Kc = 0.0156 at 400ºC 0.550 moles of HI are placed in a 2.00 L container and the system is allowed to rea
Alex_Xolod [135]

<u>Answer:</u> The concentration of hydrogen gas at equilibrium is 0.0275 M

<u>Explanation:</u>

Molarity is calculated by using the equation:

\text{Molarity}=\frac{\text{Number of moles}}{\text{Volume of solution (in L)}}

Moles of HI = 0.550 moles

Volume of container = 2.00 L

\text{Initial concentration of HI}=\frac{0.550}{2}=0.275M

For the given chemical equation:

                          2HI(g)\rightleftharpoons H_2(g)+I_2(g)

<u>Initial:</u>                  0.275

<u>At eqllm:</u>           0.275-2x      x         x

The expression of K_c for above equation follows:

K_c=\frac{[H_2][I_2]}{[HI]^2}

We are given:

K_c=0.0156

Putting values in above expression, we get:

0.0156=\frac{x\times x}{(0.275-2x)^2}\\\\x=-0.0458,0.0275

Neglecting the negative value of 'x' because concentration cannot be negative

So, equilibrium concentration of hydrogen gas = x = 0.0275 M

Hence, the concentration of hydrogen gas at equilibrium is 0.0275 M

4 0
3 years ago
6. The fusion of 4 H-1 nuclei to produce two positrons and one other nuclei.​
KIM [24]

Explanation:

Normally, fusion involves two heavy hydrogen nuclides but since we have 4 light hydrogen nuclides, two of which underwent positron emission, thus changing two protons into neutrons plus 2 positrons and 2 neutrinos. The resulting nucleus from this fusion reaction is an He-4 nucleus.

3 0
2 years ago
9. What are the advantages of using an indicator to inform pH measurements? What are the advantages of using a pH meter?
Llana [10]

Answer:

The advantages of using an indicator to inform pH measurements:

It gives a mathematically result of the pH, in addition, it gives the precise pH of solvent, and it also gives an idea of the straight of the solution also.

Now, the advantage of using a pH meter:

It is a rapid method to characterize between acids, bases. However, this method does not show how strong acid or base actually are, plus it tends to gives a range of acidity or basicity not quite accurate as a result.

3 0
3 years ago
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