Answer to Question #170855 in General Chemistry for Sarah

Question

Hello! I need to know whether these statements are true, or false and why so (if you wish).

1) The standard molar enthalpy of formation for an element in its reference form is zero

2) a formation equation is balanced such that 2 mol. of product is made

3) If system A algebraically adds system B to given system C, then  ΔHc =  ΔHa x  ΔHb according to Hess’s Law

4) A standard enthalpy change is one in which all species in the system are in their standard states.

Thank you so much!

Answer 1

1) true.

2) false, because a formation equation is balanced such that 1 mol. of product is made

3) true.

4) false, because The standard enthalpy of formation is defined as the change in enthalpy when one mole of a substance in the standard state (1 atm of pressure and 298.15 K) is formed from its pure elements under the same conditions.