{[ promptMessage ]}

Bookmark it

{[ promptMessage ]}

# c101_f10_1108 - Review Energy transfer based on...

This preview shows pages 1–5. Sign up to view the full content.

Review Energy transfer based on conservation of energy 1. Energy transfer between substances is equal. 2. Direction of energy transfer is opposite. Δ E 1 = q 1 = -q 2 = - Δ E 2 Energy transfer for physical processes Δ E = amount of substance x cost for that substance. 1. Change in temperature: q = mc Δ T (or q = nC Δ T) 2. Change in phase: q = m Δ H (or n Δ H) Energy vs. enthalpy Δ E = change in energy = energy transfer (all conditions). Δ H = change in enthalpy = energy transfer at constant pressure (usual lab conditions of atmospheric pressure).

This preview has intentionally blurred sections. Sign up to view the full version.

View Full Document
Chemistry 101 Fall 2010 2 Standard enthalpy change ( Δ H ° ) is based on a chemical equation (mole ratio) at standard conditions of 1 bar of pressure and 25 ° C. For example, H 2 O(l) H 2 O(g) Δ H ° = +44.0 kJ/mol H 2 O(g) H 2 O(l) Δ H ° = -44.0 kJ/mol ° = pressure of 1 bar and T of 25 ° C (very close to atmospheric pressure of 1 atm and room temperature, i.e., typical lab conditions) Δ H ° = standard enthalpy change for a process Energy transfer for chemical processes (Section 6.6) C 3 H 8 (g) + 5 O 2 (g) 3 CO 2 (g) + 4 H 2 O(g) Δ H ° = -2220 kJ/mol (per mole of ???) 2220 kJ is released for every 1 mol C 3 H 8 and 5 mol O 2 and 3 mol CO 2 and 4 mol H 2 O.
Chemistry 101 Fall 2010 3 Practice applying the mole ratio concept : How many grams of CO 2 are produced when 45.4 g propane are burned? How many kJ of energy are produced? MM (C 3 H 8 ) = 44.064 g/mol) MM (CO 2 ) = 44.010 g/mol 45.4 g C 3 H 8 ? g CO 2 45.4 g C 3 H 8 ? kJ

This preview has intentionally blurred sections. Sign up to view the full version.

View Full Document
Chemistry 101 Fall 2010 4 Example : conservation of energy How much water can be heated from 20.0 ° C to 100.0 ° C by burning 45.4 g propane (C 3 H 8 )?
This is the end of the preview. Sign up to access the rest of the document.

{[ snackBarMessage ]}

### Page1 / 16

c101_f10_1108 - Review Energy transfer based on...

This preview shows document pages 1 - 5. Sign up to view the full document.

View Full Document
Ask a homework question - tutors are online