Answer : 9773 kJ
Explanation:
Exothermic reactions are defined as the reactions in which energy of the product is lesser than the energy of the reactants. The total energy is released in the form of heat and 
for the reaction comes out to be negative.
To calculate the moles :
Given : Change in enthalpy on combustion of 1 mole of methanol = -1278 kJ
According to stoichiometry :
1 mole of methanol produce energy = 1278 kJ
Thus 7.647 moles of methanol produce energy =
Thus 9773 kJ of energy is produced from burning 245.0 g of methanol in excess oxygen
Answer:
1.75 × 10⁻³ M
Explanation:
Given:
Hardness = 175 mg CaCO₃/L
or mass of CaCO₃ in 1 L = 175 × 10⁻³ grams
Now,
Molar mass of CaCO₃ = 40 + 12 + ( 3 × 12 ) = 100 grams/mol
The concentration of CaCO₃ = number of moles / volume
or
= (175 × 10⁻³ / 100) / 1
or
= 1.75 × 10⁻³ M
Now,
CaCO₃ ⇒ Ca²⁺ + CO₃²⁻
1.75 × 10⁻³ M 1.75 × 10⁻³ M 1.75 × 10⁻³ M
thus,
the concentration of Ca²⁺ ions in water = 1.75 × 10⁻³ M
There are four main stages in the water cycle. They are evaporation, condensation, precipitation and collection. Let's look at each of these stages. Evaporation: This is when warmth from the sun causes water from oceans, lakes, streams, ice and soils to rise into the air and turn into water vapour (gas
