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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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How does the automatic hammer convert gravitational potential energy into kinetic energy?
Nutka1998 [239]

Answer:

Exolaiend in explanation section

Explanation:

First of all, the automatic hammer is used to drive nails into tight spaces where where we can't get a sufficient striking force if we are to use a normal regular hammer in driving the nail.

So the nail to be driven is lifted out of rest(it's position). The energy here is gravitational potential energy.

Now, when it is driven into the tight spaces, the gravitational energy would be converted to kinetic energy due to the motion and speed involved.

8 0
3 years ago
7. What are two ways to improve an experiment?
faltersainse [42]

Answer:

Stopwatches versus clocks. To improve reliability repeat the experiment multiple times according to an identical procedure. Record these steps so the experiment can be repeated at any time

Explanation:

5 0
3 years ago
Use the picture below to answer the question. What is true about the relationship between the wavelength and the frequency of th
KatRina [158]
The picture is not loading as it requires a sign in.
However, I can tell you how to solve this.

Answer:
<span>As the wavelength gets shorter (closer together), the frequency of the wave increases. 

Explanation:
The relation between frequency and wavelength can be described by the help of velocity as follows:
velocity = frequency * wavelength
This means that:
frequency = velocity / wavelength
Noting this equation, we will find that:
The frequency and the wavelength are inversely proportional to each other. This means that as the frequency increases, the wavelength decreases and vice versa.
Now, examining the choices given, we can find that the only statement showing the inverse relation between frequency and wavelength is:
</span><span>As the wavelength gets shorter (closer together), the frequency of the wave increases. 

Hope this helps :)
</span>
8 0
4 years ago
A 1.42-g sample of a pure compound with formula m2so4 was dissolved in water and treated with an ex- cess of aqueous calcium chl
solong [7]

The reaction between m_{2}SO_{4} with calcium chloride can be shown as-m_{2}SO_{4}+CaCl_{2}→CaSO_{4}↓+2mCl. The molecular weight of CaSO_{4} is 136.14g. The weight of sulfate ion is 96.06g. The molecular weight of m_{2}SO_{4} = (2×m + 96.06). From the reaction we can see that 1 mole of calcium chloride reacts with 1 molesm_{2}SO_{4} to produce 1 mole of calcium sulfate. Now 1.36g of calcium sulfate is equivalent to 1.36/136.14=9.989×10^{-3} moles of calcium sulfate.

Thus, 9.989×10^{-3} moles of m_{2}SO_{4} reacts in this reaction.

Let assume the atomic mass of m is x thus the molecular weight of m_{2}SO_{4} is 2x+96.

So we may write 9.989×10^{-3}× (2x+96) =1.42

Or, 2x + 96 = 142.146

Or, 2x = 46.146

Or, x = 23.073

Thus the atomic mass of m is 23.073. The atom (m) is sodium (Na).  

8 0
3 years ago
Why are the fruit and vegetable sections called the produce aisle?
QveST [7]
Fruits and vegetables are in the produce aisle because they are plants, and plants are producers.
Producers are organisms that create energy on their own through various processes depending on the organism. 
6 0
3 years ago
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