To help them discover new constructive forces on earth
Answer:
-800 kJ/mol
Explanation:
To solve the problem, we have to express the enthalpy of combustion (ΔHc) in kJ per mole (kJ/mol).
First, we have to calculate the moles of methane (CH₄) there are in 2.50 g of substance. For this, we divide the mass into the molecular weight Mw) of CH₄:
Mw(CH₄) = 12 g/mol C + (1 g/mol H x 4) = 16 g/mol
moles CH₄ = mass CH₄/Mw(CH₄)= 2.50 g/(16 g/mol) = 0.15625 mol CH₄
Now, we divide the heat released into the moles of CH₄ to obtain the enthalpy per mole of CH₄:
ΔHc = heat/mol CH₄ = 125 kJ/(0.15625 mol) = 800 kJ/mol
Therefore, the enthalpy of combustion of methane is -800 kJ/mol (the minus sign indicated that the heat is released).
Answer:
Solution A is 1,000 times more acidic than Sol. B
Explanation:
for pH values we use scientific notation:
-log10 c (where c is the hydrogen ion concentration) is used to notate pH value (think of it as a unit)
ie:
10^-2 is sol A 10^-5 is sol B
5-2 is 3
10^-3 = 1000
there's a diff of 1,000 between the solutions.
