The answer is B for number 1 because rather than it being an observation it is something that you know for sure happened without guessing.
the answer is B the researcher is actually adding the fertilizer and measuring it.
Answer:
(c) pH = -log [H^+]
Explanation:
pH defines the acidicity or basicity a solution.
pH also refers to hydrogen ion concentration and it is only applied to aqueous solution.
pH ranges from 0 to 14. A pH of 7 is neutral and a pH less than 7 is acidic while a pH higher than basic.
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).
