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Alenkasestr [34]
3 years ago
6

Write the ΔH system for each of the following changes in physical state

Chemistry
1 answer:
8_murik_8 [283]3 years ago
4 0

Answer:

a. positive

b. negative

c. positive

d. negative

Explanation:

In a exothermic reaction, heat is written as a product (del H is negative), whereas in an endothermic reaction heat is written on the reaction side (del H is positive).

For a, it is endothermic process. We know this because to go from solid to liquid you need to put energy into the system. When we put energy into a chemical system it is said to be an endothermic reaction.

For b, it is exothermic reaction. This is because you have to lose the extra energy to go from less ordered states (gas) to more ordered state (liquid). Gas is less ordered because its molecules are freely moving and such. Another way of thinking about this question is just putting the heat on product side and think if I was going in reverse direction I would put heat in product because I would need to add heat to liquid to turn to gas (and if heat is added to product side we know its exothermic). Two ways of thinking whichever you prefer.

The rest have similar explaination.

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using the equation 2h2+o2-->2h2o, if 192g of oxygen are produced, how many grams of hydrogen must react with it
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<span>2H2+O2-->2H2O
</span>
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Katena32 [7]

Answer:

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3 years ago
Which chemical class does phenobarbital belong to?
drek231 [11]
<span>Phenobarbital is derivative of Barbituric Acid and Barbituric Acid is derivative of Urea. (structures shown in Fig below)

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Result:
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3 0
3 years ago
If the pressure on a gas sample is tripled and the absolute temperature is quadrupled, by what factor will the volume of the sam
antoniya [11.8K]

Answer:

b. 4/3

Explanation:

Given data

  • Initial pressure: P₁
  • Initial volume: V₁
  • Initial temperature: T₁
  • Final pressure: P₂ = 3 P₁
  • Final volume: V₂
  • Final temperature: T₂ = 4 T₁

We can find by what factor will the volume of the sample change using the combined gas law.

\frac{P_{1}.V_{1}}{T_{1}} =\frac{P_{2}.V_{2}}{T_{2}}\\\frac{P_{1}.V_{1}}{T_{1}} =\frac{3P_{1}.V_{2}}{4T_{1}}\\V_{1} =\frac{3V_{2}}{4}\\V_{2}=4/3 V_{1}

7 0
3 years ago
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