Part 1 - Homework Review Flashcards
(14 cards)
Identify the solute and the solvent in each solution of the following 10.0g NaCl and 100.0g H20
Nacl - solute H20 - solvent
Identify the solute and the solvent in each solution of the following 50.0 mL of ethanol and 10.0 mL H20
H20 - solute ethanol - solvent
Identify the solute and the solvent in each solution of the following 0.20 L of O2 and 0.80 L N2
O2 - solute N2 - solvent
Water is a polar solvent and carbon tetrachloride is a nonpolar solvent. In which solvent is each of the following more likely to be soluble?
for polar substances, water is better solvent (bc polar) for nonpolar substances, ethanol is better solvent (bc nonpolar)
State polar or nonpolar of CaCo3, retinol, sucrose, cholesterol, hexane, CCl4
CaCo3 - polar retinol - nonpolar sucrose - polar cholesterol - nonpolar hexane - nonpolar CCl4 - nonpolar
What is the sign for endothermic and exothermic reactions?
Exothermic: deltaH is negative
Endothermic: deltaH is positive
Determine the sign of deltaH for the following reactions or processes.
a. the combustion of butane
b. the freezing of water
c. when ammonium nitrate solid dissolves in water, the solution gets cold
d. the sublimation of CO2
a. the combustion of butane
releases heat, deltaH is negative
b. the freezing of water
liquid (more energy) ==> solid (less energy)
deltaH is negative
c. when ammonium nitrate solid dissolves in water, the solution gets cold
It gets cold because its absorbing heat, deltaH is positive
d. the sublimation of CO2
solid (less energy) ==> gas (more energy)
deltaH is positive
Explain the following observations
More sugar dissolves in hot tea than in iced tea
Solubility is temperature dependent
So with a higher temperature more sugar dissolves
Explain the following observations
Champagne in a warm room goes flat
Solubility of gases decreases as temperature increases because the gas particles gain kinetic energy and escape the liquid
Explain the following observation
a warm can of soda has more spray when opened than a cold one
higher temperature lowers gas solubility
so more CO2 (g) instead CO2 (l)
When the can of warm soda is opened, CO2 is released which causes more spray
Decide whether liquid hexane or liquid methanol is the more appropriate solvent for the substances grease and potassium iodide
hexane is the most appropriate solvent for grease because both are nonpolar
methanol is the most appropriate solvent for potassium iodide because both are nonpolar
a soft drink is bottled so that at 25 degrees Celcius contains CO2 gas at a pressure of 5.0 atm over the liquid. Assuming the partial pressure of CO2 in the atmosphere is 4.0 x 10^-4 atm, calculate the equilibrium concentrations of CO2 in the soda both before or after the bottle is opened. The Henry’s law constant for CO2 in aqueous solution is 0.031 M/atm at 25 degrees Celcius
How do we use the chart to determine whether each reaction will be saturated or unsaturated?
a. adding 25g of KCL to 100g H20
b. adding 11g NaNO3 to 25g H20
c. adding 400g sugar to 125g H20
First we need to look at units of solubility in table of
(values at a temperature/100g)
Steps
1. find the solubility (values at a temperature/100g)
2. Find what we have. (Solute amount/solvent amount)
3. Compare what we calculated to solubility to determine if it’s unsaturated or saturated
a. adding 25g of KCL to 100g H20
Solubility: (34g/100g). We have (25g/100g). 0.25 < 0.34 ==> unsaturated
b. adding 11g NaNO3 to 25g H20
Solubility: (88g/100g). We have (11g/25g). 0.44 < 0.88 ==> unsaturated
c. adding 400g sugar to 125g H20
Solubility: (402/100g). We have (400g/125g). 3.2 > 2.04 ==> supersaturated
Is a solution that contains 175g K2C2O2 and 250g of water at 50 degrees Celsius saturated or unsaturated? The solubility is 0.3
First we need to look at units of solubility in table of
(values at a temperature/100g)
Steps
1. find the solubility (values at a temperature/100g)
2. Find what we have. (Solute amount/solvent amount)
3. Compare what we calculated to solubility to determine if it’s unsaturated or saturated
(175g K2C2O2 / 250g H20) = 0.7
0.7 > 0.3 ==> supersaturated
