The answer is A hopefully this help you
The strong Base with a pH of 12 is reduced by 4 units upon being added with solution Y. If you added a strong acid to the strong base, all ions are present in the solution, yes? So every OH- is neutralised by every H+ for example, meaning the resultant pH should be 7. The resultant pH is only 8 however, so solution Y must be a <em>weak acid </em>only!
Answer:
Doing an Endothermic reaction, energy is absorbed from surroundings
Explanation:
Endothermic reactions:
The type of reactions in which energy is absorbed are called endothermic reactions.
In this type of reaction energy needed to break the bond are higher than the energy released during bond formation.
For example:
C + H₂O → CO + H₂
ΔH = +131 kj/mol
it can be written as,
C + H₂O + 131 kj/mol → CO + H₂
we can see that 131 kj/mol energy is taken by the reactants. So energy is absorbed from surrounding.
Exothermic reaction:
The type of reactions in which energy is released are called exothermic reactions.
In this type of reaction energy needed to break the bonds are less than the energy released during the bond formation.
For example:
Chemical equation:
C + O₂ → CO₂
ΔH = -393 Kj/mol
it can be written as,
C + O₂ → CO₂ + 393 Kj/mol
127.88 grams of ethanol were present at the beginning of the reaction
Explanation:
Firstly, let's make the combustion reaction:
C₂H₅OH + 3O₂ → 2CO₂ + 3H₂O
By 1 mol of ethanol, you can make 3 mole of water.
Mole of water = Water mass / Molar mass
150g / 18g/m = 8.3 mole
3 mole of water came from 1 mol of ethanol
8.3 mole came from (8.3 .1)/3 = 2.78 mole of ethanol
Molar mass ethanol = 46 g/m
Mole . molar mass = mass
2.78 m . 46g/m = 127.88 g
