Answer:
a) Warmer
b) Exothermic
c) -10.71 kJ
Explanation:
The reaction:
KOH(s) → KOH(aq) + 43 kJ/mol
It is an exothermic reaction since the reaction liberates 43 kJ per mol of KOH dissolved.
Hence, the dissolution of potassium hydroxide pellets to water provokes that the beaker gets warmer for being an exothermic reaction.
The enthalpy change for the dissolution of 14 g of KOH is:
<u>Where:</u>
m: is the mass of KOH = 14 g
M: is the molar mass = 56.1056 g/mol
The enthalpy change is:
The minus sign of 43 is because the reaction is exothermic.
I hope it helps you!
Answer:
MIXTURE
Explanation:
A mixture is a substance composed of a combination of other different substances. These component(s) of a mixture are physically combined, meaning that there is no chemical linkage between the individual components/constituents of a mixture.
This is the case of the gravel described in this question. The components of gravel can be separated using physical means because they are not chemically bonded to one another, hence, no chemical reactions are needed to separate different parts of gravel into pure substances. This makes gravel a MIXTURE.
An acid in chemistry is anything with a pH level lower than 7.
Answer:
The mass of potassium required to produce a known mass of potassium chloride
Explanation:
Stoichiometry deals with the relationship between amount of substances, mass of substances or volume of substances required in a chemical reaction. Stoichiometric relationships may involve reactants alone or reactants and products. These relationships are normally in the form of simple proportion.
A typical example is our answer option, the mass of potassium required could be used to determine the mass of potassium chloride produced after a balanced reaction equation is written.
(1) The quantity of heat required to melt 175 g Cu is 35.88 kJ.
(2) The substance that releases 21.2 kJ of energy when 1.42 mol of it freezes is iron.
<h3>
What is heat of fusion?</h3>
Heat of fusion is the energy required to melt 1 mole of a substance.
<h3>What is heat of vaporization?</h3>
The heat energy required to vaporize 1 mole of a substance has been heat of vaporization.
Heat of fusion of copper (Cu) is given as 13 kJ/mol
Number of moles of 175 g of copper = 175/63.5 = 2.76 moles
Q = nΔH
Q = 2.76 mol x 13 kJ/mol = 35.88 kJ
Thus, the quantity of heat required to melt 175 g Cu is 35.88 kJ.
<h3>Heat of fusion of the substance</h3>
ΔH(fus) = Q/n
where;
- n is number of moles
- Q is quantity of heat released
ΔH(fus) = 21.2 kJ / 1.42 mol
ΔH(fus) = 14.93 kJ/mol
From the table the substance with latent heat of fusion of 14.9 kJ/mol is iron.
Thus, the substance that releases 21.2 kJ of energy when 1.42 mol of it freezes is iron.
Learn more heat of fusion here: brainly.com/question/87248
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