40. What is the mass of 3 moles of H 2 O

54g

Explanation:

Given parameters:

Number of moles of H₂O  = 3 moles

Unknown:

mass of water  = ?

Solution:

To solve this problem, we use the expression below:

         mass  = number of moles x molar mass

Molar mass of H₂O  = 2(1)  + 16  = 18g/mol

Mass of water  = 3 x 18  = 54g

r just means there's a number of carbon in teh chain. for example rcooh means that after x number of carbon, the chain ends with cooh.

explanation:

answer: enthalpy

explanation:

for a exothermic reaction, the energy is released i.e. the energy of the products is lower than the energy of the reactants.

= enthaply

= energy of products

= energy of reactants

as , thus comes out to be negative. negative value of enthalpy shows that the reaction is exothermic.