Answer:

Explanation:
Hello,
In this case, since at 60 °C, 108 grams of ammonium bromide are completely dissolved in 100 grams of water for a saturated solution, once it is cooled to 30 °C, wherein only 83.2 grams are completely dissolved in 100 grams of water, the following mass will precipitate:

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Answer:
The exact molecular mass is 18.01528 g/mol
Explanation:
Find this by adding the molecular masses of two hydrogen atoms and one oxygen atom.
Answer:
C
Explanation:
A negative deltaH means that the reaction has to give up heat in order to happen. You have to treat deltaH as a reactant. So the question is do you need to add heat to the reactants to make the products. If you do, deltaH is plus.
Heat is required to make a solid go to a gas. deltaH is plus. A is not the answer.
A lot of heat is required for B (something like 400 Kj / mole. Like A, deltaH is plus and B is not the answer.
C: The liquid has to give up heat in order for the this reaction to take place. C is the answer.
D requires heat. It is not the answer.
Answer:
The heat of reaction when hydrogen and oxygen combine to form water is :
<u>C. 571.6 kJ</u>
Explanation:
Enthalpy Change = The enthalpy change for the formation of 1 mole of the substance from their standard state is called the enthalpy of formation.
This is intensive quantity as it is fixed for 1 mole .
Intensive properties = Those properties which are independent on the amount of the substance are intensive properties.
The value of these quantities does not get halve if you divide the substance into two equal parts. example , density, refractive index.
However , the enthalpy of reaction is extensive. Because on increasing the amount the value of the enthalpy also get doubles
Hence for this reaction :

Its value is -285.8 kJ for 1 mole
And here two moles are present . so the value of molar enthalpy is:
-285.8 x 2 = -571.6 kJ