# F335 The Oceans

What are the reactions for CO2 dissolving in water?
CO2 (g) CO2 (aq). CO2 (aq) +H2O (l) H+ (aq) HCO3- (aq). HCO3- (aq) H+ (aq) + CO3 2- (aq). Overall: CO2 (g) + H2O (l) 2H+(aq) + CO3 2- (aq)
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What methods can help slow down the increase of atmospheric CO2?
More economical use of fossil fuels. Using alternative fuels. Capture and storage or CO2. Increased levels of photosynthesis
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How do you work out the entropy change of a reaction?
entropy of products - entropy of reactants
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How do you work out the entropy change of the surroundings?
-enthalpy change / temp (K)
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What conclusions can be made if the total entropy change is (a) positive or (b) 0
(a) the reaction will occur spontaneously. (b) the reaction is at equilibrium
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What is ΔH LE? Why is it always negative?
The enthalpy change when 1 mole of a solid is formed from its separate gaseous ions. Because it involves the formation of ionic bonds
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What is ΔH hyd? Why is it always negative?
The enthalpy change when an aqueous solution is formed from 1 mole of gaseous ions. It involves ion-dipole bonds forming. The greater the enthalpy change, the stronger the ion-dipole attractions and the greater number of h2o molecules surrounding ion
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What is ΔH solution?
The enthalpy change when 1 mole of a solute dissolves to form a dilute solution. = ΔH hyd (cation) + ΔH hyd (anion) - ΔH LE
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What happens if the ΔH solution is negative or slightly positive?
The solid will usually dissolve because the entropy change will be generally favourable
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What happens if the ΔH solution is large and positive?
The solid won't dissolve, even though the entropy change will be generally favourable, because the energy needed is too much
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What is ΔH solv?
The enthalpy change when a solution is formed from 1 mole of gaseous ions using a solvent other than water
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What's the term used for aqueous solutions of strong acids where almost all of the acid molecules donate their protons? What are some examples of strong acids that do this?
Complete dissociation. HCl, H2SO4, HNO3
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What's Ka?
The acidity constant (acid dissociation constant). The greater the value, the stronger the acid. It equals [products]/[reactants]
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How can pH be calculated?
-log[H+(aq)]
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What's Kw?
Symbol used to represent the ionic product for water. = [H+(aq)][OH-(aq] = 1 x 10^-14 mol^2 dm^-6 at 298 K
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What are buffer solutions?
Solutions that have an almost constant pH. The contain large amounts of proton donor and acceptor
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What calculation can be used with buffers?
Ka = [H+ (aq)] x ([salt]/[acid])
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## Other cards in this set

### Card 2

#### Front

What methods can help slow down the increase of atmospheric CO2?

#### Back

More economical use of fossil fuels. Using alternative fuels. Capture and storage or CO2. Increased levels of photosynthesis

### Card 3

#### Front

How do you work out the entropy change of a reaction?

### Card 4

#### Front

How do you work out the entropy change of the surroundings?

### Card 5

#### Front

What conclusions can be made if the total entropy change is (a) positive or (b) 0