Answer:
Molar mass of Ca = 40 g / mol , given 123 g Ca is 123/40= 3.075 moles,
1 mole = 6.022 * 10^23 atoms, so 3.075 moles Ca= 18.51*10^23 atoms
Explanation:
the answer is thermal.......
Answer:
Explanation:
13 ) symbol of enthalpy change = Δ H .
14 ) enthalpy change is nothing but heat absorbed or evolved .
During fusion enthalpy change
Δ H .= m Lf , m is mass and Ls is latent heat of fusion
During evaporation, enthalpy change
Δ H .= m Lv , m is mass and Lv is latent heat of evaporation
during temperature rise , enthalpy change
Δ H = m c Δ T
In case of gas , enthalpy change can be calculated by the following relation
Δ H = Δ E + W , Δ E is change in internal energy , W is work done by gas.
15 ) When enthalpy change is negative , that means heat is released to the environment .So reaction is called exothermic .
when heat is absorbed enthalpy change is positive . Reaction is endothermic.