Chapter 5 Review Questions Flashcards
Life on our planet depends on water. Explain each of the following statements:
A) bodies of water act as heat reservoirs, moderating climate
B) ice protects ecosystems in lakes because it floats rather than sinks
A) because water has such a high specific heat, it can moderate climate by capturing and absorbing heat from surrounding land and air
B) if ice were denser than liquid water, it would sink as it forms. Meaning lakes would freeze, killing all forms of life
In some cases, the boiling point of a substance increases with its molar mass
A) does this hold true for hydrocarbons? Explain with examples
B) based on the molar mass of h2o, n2, o2, and co2, which would you expect to have the lowest boiling point
C) unlike n2, o2, and co2, water is a liquid at room temperature, explain
A) yes, distillation towers at a petroleum refinery separate hydrocarbons of different sizes by their boiling points
B) h2o would have the lowest boiling point because it’s molar mass is the lowest
C) water is a polar molecule while the rest are non polar, it’s geometry and polar covalent bonds contribute to the formation of strong intermolecular forces
What is a polar covalent bond?
A polar bond forms between atoms that have highly different electronegativity values.
What is density?
The degree of compactness of a substance
Consider these Liquids and their density:
Dishwashing detergent- 1.03 g/mL
Maple syrup- 1.37 g/mL
Vegetable oil- .91 g/mL
A) if you pour equal volumes of these three liquids into a 250-mL graduated cylinder, in what order should you add the liquids to create three separate layers. Explain
B) predict what would happen if a volume of water equal to the other liquids were poured into the cylinder in part a. And the condenses then were mixed vigorously.
A) add the liquids from most to least dense to prevent mixing the liquids.
Solutions can be tested for conductivity using this type of apparatus:
Predict what will happen when each of these dilute solutions is tested for conductivity. Explain your predictions briefly
A) CaCl2
B) C2H5OH
C) H2SO4
A) the solution will conduct electricity, it is a soluble salt and releases ions
B) the solution will not conduct electricity, although ethanol is soluble in water, it is covalent compound and does not form ions
C) the solution will conduct electricity, it releases ions when it dissolves
(Table 5.5) What is the solubility of the given compounds:
Group 1 metals, NH4+… nitrates, chlorides, sulfates, carbonates, hydroxides, sulfides
Group 1, NH4+ & nitrates are all soluble
Chlorides and sulfates and most soluble
Carbonates, hydroxides, and sulfides are mostly insoluble
Based on Table 5.5, which compounds are likely to be water-soluble?
A) KC2H3O2
B) LiOH
C) Ca(NO3)2
D) Na2SO4
All compounds are water soluble
What are the qualities of an acid, base, and neutral solution? What are these solutions?
A) HI
B) NaCl
C) NH4OH
A) is an acid because it release hydrogen ions
B) is neutral, neutral solutions release both hydrogen and hydroxide ions, or none at all
C) is a basic solution because it releases hydroxide ions
In each pair below, the [H+] is different. By what factor of 10 is it different?
Ph = 6 and ph = 8 -> 8 is 100 times more than that of a pH of 6
PH = 5.5 and pH = 6.5 -> is 10 times more than that of a pH of 5.5 since they are one apart
[H+] = 1 x 10^-8 M and [H+] = 1 x 10^-6 is 100 times more seeing as they are 2 apart
[OH-] = 1 x 10^-2 M and [OH-] = 1 x 10^-3 is 10 times more seeing as they are 1 apart
Which gas is dissolved in water to produce each of the following acids?
A) carbonic acid, H2CO3
B) sulfurous acid, H2SO3
A) Carbon dioxide, CO2 (CO3 + H20 —-> H2CO3)
B) Sulfur dioxide, SO2 (SO2 + H20 ——-> H2S3)
Propose an explanation for the fact that NH3, like H2O, has an unexpectedly high specific heat.
Like water, NH3, is a polar molecule. It has polar N-H bonds and a trigonal pyramidal geometry. Therefore, despite its lower molar mass, considerable energy must be added to liquid NH3 to overcome the intermolecular forces (hydrogen bonding) among NH3 molecules
Health goals for contaminants in drinking water are expressed as MCLG, or maximum contaminant level goals. Legal limits are given as MCL, or maximum contaminant levels. How are MCLG and MCL related for a given contaminant.
The goal and legal limit are usually the same. However, the levels may differ when it is not practical or possible to achieve the heath goal as set by the MCLG. This sometimes is the case for carcinogens
