Answer:
Explanation:
The second one is quite simple. CH4 (methane) is the main component for natural gas. It is used to heat houses in many many areas. It it heats a house, it must give off heat. It is exothermic.
The first one is much less common and hard to reason. I think it is easier to see the reverse reaction
O2 ===> 2O
O2 is a fairly stable molecule. It takes energy to break the molecules apart. That makes this reaction endothermic.
So the reaction you are given is just the opposite. It must be exothermic.
2O ===> O2 must be exothermic.
The amount of KNO₃ precipitated out of solution when you cooled the solution from 100°C to -22°C is obtained from the solubility curve
<h3>What is a solubility curve?</h3>
A solubility curve is a curve of the solubility of a solute against temperature.
The solubility curve shows that the solubility of different solute at different temperatures.
The solubility curve of KNO₃ is as shown. Solubility at 100 °C and -22 °C is not shown in the curve.
However, the amount of KNO₃ precipitated out of solution when cooled the solution from 100 °C to -22 °C can be determined by subtracting the amount of solute dissolve at -22 °C from that dissolved at 100 °C.
In conclusion, the solubility curve is used to determined the amount of solute dissolved in a given volume of solvent at different temperatures.
Learn more about solubility curve at: brainly.com/question/928930
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When copper (ii) oxide is heated in presence of hydrogen gas it produces copper metal and water vapor.
that is
CuO + H2 = Cu + H2O
The moles of copper metal produced is calculated as below
find the moles of CUO used
moles = mass/molar mass
=5.6/79.5 =0.07 moles
by use of mole ratio between CUO:Cu which is 1:1 the moles of Cu is also
=0.007 moles of Cu