1 / 10

Experimental Enthalpy Changes

Experimental Enthalpy Changes. q = mc Δ t. Copper Sulphate + Zinc. 25cm 3 of 0.5 mol dm -3 CuSO 4 1g zinc (excess) Temp rise 20 o C. Temp. Time (min). Calculate heat energy. q = m c Δ t. q = heat energy change (J) m = 25g (assuming density = 1g/cm 3 ) c = 4.18Jg -1 K -1 Δ t = 20.

makan
Download Presentation

Experimental Enthalpy Changes

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript


  1. Experimental Enthalpy Changes q = mcΔt

  2. Copper Sulphate + Zinc • 25cm3 of 0.5 mol dm-3 CuSO4 • 1g zinc (excess) • Temp rise 20oC Temp Time (min)

  3. Calculate heat energy q = m c Δt q = heat energy change (J) m = 25g (assuming density = 1g/cm3) c = 4.18Jg-1K-1 Δt = 20 q = 25 x 4.18 x 20 q = 2090 J = 2.09 kJ

  4. Calculate no moles used n = c x v n = no moles v = volume used (dm-3) c = concentration (0.5 moldm-3) n = 0.5 x 25/1000 n = 0.0125

  5. Calculate ΔH in kJmol-1 ΔH = q / n n = no moles q = energy change (kJ) ΔH = 2.09 / 0.0125 ΔH = - 167.2 kJmol-1 exothermic

  6. Citric Acid & Sodium hydrogen Carbonate • 25cm3 of 0.4 mol dm-3 citric acid • 3g NaHCO3 (excess) • Temp drop 9oC

  7. Calculate heat energy q = m c Δt q = heat energy change (J) m = 25g (assuming density = 1g/cm3) c = 4.18Jg-1K-1 Δt = 9 q = 25 x 4.18 x 9 q = 940.5 J = 0.9405 kJ

  8. Calculate no moles used n = c x v n = no moles v = volume used (dm-3) c = concentration (0.5 moldm-3) n = 0.4 x 25/1000 n = 0.01

  9. Calculate ΔH in kJmol-1 ΔH = q / n n = no moles q = energy change (kJ) ΔH = 0.9405 / 0.01 ΔH = + 94 kJmol-1 endothermic

More Related