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1) Answer: A hot pack feels warm when chemicals in it combine.
Explanation: Reactions or process in which heat is released(produced) are known as exothermic reactions or process and those in which the heat is absorbed are known as endothermic reactions or process.
If a beaker feels cools when chemical in it react then it means the chemicals have absorbed the heat energy from its surroundings and so it is an example of an endothermic process.
A hot pack feels warm when chemicals in it combine means the energy is released in the chemical reaction and so it is an example of an exothermic process.
Plants use the sun's energy for photosynthesis which is a process of forming food for the plants. Energy acts as a reactant in this process and so it is an example of endothermic process.
Frying an egg by heating it on a stove is an example of an endothermic process as the heat is required to fry the egg.
So, the only exothermic process is the second one, "A hot pack feels warm when chemicals in it combine."
2) In the given equation, heat is written as a product means the heat is released in the equation and so it is an example of an exothermic reaction.
So, the correct choice is the last one " It is exothermic because energy is released."
Answer:The answer to this question comes from experiments done by the scientist Robert Boyle in an effort to improve air pumps. In the 1600's, Boyle measured the volumes of gases at different pressures. Boyle found that when the pressure of gas at a constant temperature is increased, the volume of the gas decreases. when the pressure of gas is decreased, the volume increases. this relationship between pressure and volume is called Boyle's law.
Explanation: So, at constant temperature, the answer to your answer is: the volume decreases in the same ratio as the ratio of pressure increases.
BUT, in general, there is not a single answer to your question. It depend by the context.
For example, if you put the gas in a rigid steel tank (volume is constant), you can heat the gas, so provoking a pressure increase. But you won't get any change in volume.
Or, if you heat the gas in a partially elastic vessel (as a tire or a soccer ball) you will get both an increase of volume AND an increase of pressure.
FINALLY if you inflate a bubblegum ball, the volume will be increased without any change in pressure and temperature, because you have increased the NUMBER of molecules in the balloon.
There are many other ways to change volume and pressure of a gas that are different from the Boyle experiment.
NH₃:
N = 8*10²²
NA = 6.02*10²³
n = N/NA = 8*10²²/6.02*10²³ ≈ 1.33*10⁻¹=0.133mol
O₂:
N=7*10²²
NA = 6.02*10²³
n = N/NA = 7*10²²/6.02*10²³ = 1.16*10⁻¹=0.116mol
4NH₃ <span>+ 3O</span>₂ ⇒<span> 2N</span>₂<span> + 6H</span>₂<span>O
</span>4mol : 3mol : 2mol
0.133mol : 0.116mol : 0,0665mol
limiting reactant
N₂:
n = 0.0665mol
M = 28g/mol
m = n*M = 0.0665mol*28g/mol = <u>1,862g</u>
Answer:
2445 L
Explanation:
Given:
Pressure = 1.60 atm
Temperature = 298 K
Volume = ?
n = 160 mol
Using ideal gas equation as:
where,
P is the pressure
V is the volume
n is the number of moles
T is the temperature
R is Gas constant having value = 08206 L.atm/K.mol
Applying the equation as:
1.60 atm × V = 160 mol × 0.08206 L.atm/K.mol × 298 K
<u>⇒V = 2445.39 L</u>
Answer to four significant digits, Volume = 2445 L
