Multiple choice

For which of the following reactions ∆H is equal to ∆U?

  1. <span style="font-size:11.0pt;line-height:115%;font-family:"Calibri","sans-serif";mso-ascii-theme-font:minor-latin;mso-fareast-font-family:Calibri;mso-fareast-theme-font:minor-latin;mso-hansi-theme-font:minor-latin;mso-bidi-theme-font:minor-latin;mso-ansi-language:EN-US;mso-fareast-language:EN-US;mso-bidi-language:AR-SA">H2(g) + I2(g) → 2HI(g)

  2. <span style="font-size:11.0pt;line-height:115%;font-family:"Calibri","sans-serif";mso-ascii-theme-font:minor-latin;mso-fareast-font-family:Calibri;mso-fareast-theme-font:minor-latin;mso-hansi-theme-font:minor-latin;mso-bidi-theme-font:minor-latin;mso-ansi-language:EN-US;mso-fareast-language:EN-US;mso-bidi-language:AR-SA">H2(g) + 1/2O2(g) → H2O(l)

  3. <span style="font-size:11.0pt;line-height:115%;font-family:"Calibri","sans-serif";mso-ascii-theme-font:minor-latin;mso-fareast-font-family:Calibri;mso-fareast-theme-font:minor-latin;mso-hansi-theme-font:minor-latin;mso-bidi-theme-font:minor-latin;mso-ansi-language:EN-US;mso-fareast-language:EN-US;mso-bidi-language:AR-SA">2SO3(g) → 2SO2(g) +O2(g)

  4. <span style="font-size:11.0pt;line-height:115%;font-family:"Calibri","sans-serif";mso-ascii-theme-font:minor-latin;mso-fareast-font-family:Calibri;mso-fareast-theme-font:minor-latin;mso-hansi-theme-font:minor-latin;mso-bidi-theme-font:minor-latin;mso-ansi-language:EN-US;mso-fareast-language:EN-US;mso-bidi-language:AR-SA">2NO2(g) → N2O4(g)
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

The correct relation between ∆H and ∆U is given by the relation ∆H = ∆U +∆ngRT…………..where ∆ng is the difference in number of moles of gaseous products and reactants. For the given reaction ∆ng = (2-[1+1]) = 0, so ∆H = ∆U.

Keep practicing — related questions