CHEM 1010 CHPT 10
What is the partial pressure of O2 in the air around us if the molar concentration of O2 in a sample of river water is 14 mg/L and the kH for O2 in H2O is equal to 1.3 x 10^-3 mol/L•atm?
0.34
Choose the solids that will float on pure water and drag them onto the water.
0.96 g/cm^3 0.91 g/cm^3 1.00 g/cm^3
here's a recipe for apple pie using the metric system to describe the amounts of ingredients that are needed. use the internet to convert
1.5 kg sliced apples: 8.25 cups 150 g granulated sugar: 3/4 cup 25 mL cornstarch: 1.75 tablespoons 4 mL ground cinnamon: 3/4 teaspoons 40 g butter: 2.75 tablespoons
The partial pressure of O2 in the air around us is 0.21 atm. What is the molar concentration of O2 in a sample of river water at normal atmospheric pressure if the value of kH for O2 in H2O is equal to 1.3 x 10^ -3 mol/L •atm?
2.7 x 10^ -4 mol/L C = 1.3 x 10^ -3 mol x 0.21 atm L•atm
the perfect quesadilla can be made with two large flour tortillas (200 g per tortilla) and 1 cup of cheese (50 g). Identify the limiting reagent and excess reagent in making quesadillas with the ingredients shown below.
450 g cheese Excess Reagent 10 tortillas Limiting Reagent
A cookie recipe calls for 1/2 cup of butter, 1 cup of sugar, two eggs, and one and 1/4 cups of flour for two dozen cookies. You have 1 1/2 cups of butter, 2 1/2 cups of sugar, 6 eggs, and 4 cups of flour. How many cookies can you bake?
60 cookies
Why do bubbles rush out of a carbonated beverage when the container is opened?
CO2 becomes less soluble in the beverage when the pressure is released
Theobromine
Carboxylic Acid
Rank the following aqueous Salt solutions in order of boiling point, from the lowest to the highest
Lowest Boiling Point 1.0 M NaCl(aq) 0.1 M NaCl(aq) 0.5 M KCl(aq) Highest Boiling Point 1.0 M CaCl2(aq) 2.0 M CaCl2(aq)
Flavonol
Methyl
Tryptophan
Phenyl
Group the following acids as strong or weak by dragging them to the appropriate area.
Strong Acids hydrochloric acid hydrobromic acid nitric acid sulfuric acid Weak Acids acetic acid formic acid chlorous acid hydrofluoric acid hydrocyanic acid
Choose the molecule that contains the following functional groups: carboxylic acid, phenyl group and methyl group.
Theobromine Carboxylic Acid Tryptophan Phenyl Flavonol Methyl
Describe the behavior of water molecules from the interaction with electromagnetic radiation in the UV, IR, microwave, and radio regions. Choose between Bond breaking, Nothing, Molecular Vibration, or Molecular Rotation.
UV Bond Breaking IR Molecular Vibration Microwave Molecular Rotation Radio Nothing
The relationship between pressure and temperature is _____.
a directly proportional relationship
The alcoholic mixture produced by fermentation of sugars can be distilled, a process that separates liquids based on their _____. This allows ethanol to be separated from water, resulting in a solution with a _____ alcoholic content.
boiling points; higher
During the distillation process, the distillate is cooled in _____ the to form a liquid that can be collected.
condenser
Ethanol has a polar -OH group allowing it to dissolve readily in water and a small hydrocarbon portion, which allows it to interact with nonpolar solvents and cell membranes. We describe ethanol as having _____.
dual polarity
Mayonnaise is an example of a(n) _____ in which a nonpolar substance is dispersed in a polar solvent. This normally incompatible system is stabilized by the _____ in the mayonnaise.
emulsion; egg yolk
The process in which yeast converts sugars to alcohol and CO2 is called _____.
fermentation fermentation is an anaerobic process.
When room temperature pasta is placed in boiling water, heat flows _____, causing the pasta to cook.
from the water to the pasta Heat always flows spontaneously from the object or substance at higher temperature to that at lower temperature. Thus heat from the boiling water flows to the pasta, causing the pasta to cook. The surrounding air is generally (hopefully) cooler than boiling water. Heat always flows spontaneously from the object or substance at higher temperature to that at lower temperature.
A foam is formed when a _____ is trapped in a _____.
gas; liquid or solid
Drying and curing are suitable methods of food preservation because _____.
harmful microbes also rely on water to survive
When a carbonated beverage is sealed, the pressure on the beverage is _____ than atmospheric pressure. When the can is opened, the pressure on the liquid _____ and the dissolved CO2 bubbles out as its solubility decreases.
higher; decreases
A _____ is an instrument that measures changes in the density of a liquid.
hydrometer
Henry's law states that the amount of gas dissolved in a given volume of solution will _____ when the pressure increases.
increase
During a phase change such as liquid to gas for a molecular substance, the temperature of the system_____.
is unchanged. Temperature remains unchanged during a phase change as long as the source of heat or cooling is not removed. This is because heat transferred during a phase change is involved in breaking or forming intermolecular attractions and is not used to change the kinetic energy of the molecules.
The alcoholic solution produced by fermentation can be distilled by heating in a still. The compounds with _____ boiling points evaporate first and so the distillate contains a _____ concentration of ethanol than the liquid left behind.
lower; greater
Microwave radiation has a _____ energy then uv, ir, or visible radiation and will therefore _____ in the molecules in food during cooking.
lower; not break bonds microwave radiation is not sufficient to cause rupturing of individual chemical bonds. Instead, the microwave radiation is absorbed by the water, fat, and sugar molecules in food which causes these molecules to rotate very fast causing them to easily bump into and rub against one another, resulting in the production of heat due to frictional forces.
A hydrometer, which measures changes in liquid density, would most typically be used for _____.
monitoring a fermentation process in beer or wine making
Oil does not readily mix with water because oil is _____ while water is _____.
nonpolar; polar
The statement "like dissolves in like" means that _____.
polar substances will dissolve most readily in polar solvents
When determining food readiness, methods such as dropping cooked sugar mixture into cold water to determine its cooking stage are _____ methods, whereas the use of a thermometer to measure temperature is a _____ method.
qualitative; quantitative
A refractometer measures the extent to which a solution refracts (changes the direction of) light, which is expressed by its _____. This quantity _____ as the specific gravity of the solution increases.
refractive index; increases
A pressure cooker allows food to cook faster because _____.
the boiling point of water is higher under higher pressure
Henry's Law expresses the relationship between the concentration of a gas in solution and the pressure on the solution. Which of the following options correctly describe the quantities in Henry's Law equation, given below? Henry's Law: C = kP
• C is the concentration of the gas in moles per liter • k is called the Henry's Law constant for a particular gas/solvent combination • P is the pressure measured in atmospheres
Which of the following substances maybe used in the salting or salt-curing of foods?
• NaCl • nitrite salts • nitrate salts
When food is salted for preserving _____.
• NaCl added to the food causes water to be removed • NO formed from nitrites and nitrates binds to the iron in hemoglobin • nitrites and nitrates are antioxidants and kill bacteria
A thermometer would be most helpful or necessary when preparing _____.
• candy • roasted meat • fried chicken
Compared to UV, IR, and visible radiation, microwave radiation _____.
• causes molecules to rotate rather than breaking bonds • has a lower energy
Which of the following are qualitative methods of determining food readiness?
• checking the degree of browning when frying an egg • the "softball test" for candy • the "fist test" for grilled meat
A refractometer _____.
• detects the bending of light in a solution • can be used to determine specific gravity • is often used to determine the sugar content of a solution
In cooking, thermometers are most typically used for _____.
• ensuring the oven is at the correct temperature • measuring the temperature of a sugar mixture when making candy • determining the internal temperature of meat
In the process of fermentation _____.
• glucose and other sugars are converted to ethanol • CO2 is produced • a microorganism such as yeast is required
A foam maybe produced by _____.
• injecting a gas into a thickened liquid at higher pressure • beating air into a solution with a spoon or beater
A liquid boils when it's vapor pressure equals the external pressure. At higher altitudes the atmospheric pressure is lower and the liquid therefore boils at a _____ temperature. Food May therefore take _____ to cook at higher altitudes.
• lower; longer If the external pressure is lower the vapor pressure of the liquid does not need to rise as much to be equal to the external pressure. The liquid therefore boils at a lower temperature.
Drying and curing preserved foods by _____.
• removing • adding salt the salt added in salt curing techniques causes water to be removed from the food. drying involves no cooking, although smoking is a heat transfer process.
Which of the following correctly describes steps in the processing of coffee?
• roasting of coffee beans improves the flavor of coffee • more flavor is extracted from finely ground coffee beans
Ethanol, like other alcohols, has dual polarity because _____.
• the carbon portion of the molecule can interact with nonpolar substances • the polar -OH group can interact with the H2O and other polar substances
In the sous vide method of cooking _____.
• the food to be cooked is vacuum sealed • food is cooked at the same temperature at which it is to be eaten
Mayonnaise is an example of an emulsion which _____.
• would settle out unless stabilized • has a nonpolar substance dispersed in a polar substance
