CHEZ 303 Quiz 1

During this experiment 1, you should never allow the pressure in the flask to exceed ______ kPa.

120

Which of the following is an acceptable procedure for making 250 mL of a 2.0 M aqueous NaCl solution from the pure salt.

Add 29.2 g of NaCl to approximately 125 mL of water in a 250 mL volumetric flask. 2. Dissolve the salt. 3. Fill to just below the mark with water. 4. Stopper the flask and invert three times to mix . 5. Fill to the mark with water. 6. Again stopper the flask and invert three times to mix.

The following equation defines the reaction rate between hydrochloric acid and magnesium. Any symbol, or combination of symbols, that can be used to represent a number is deemed to be parameter of an equation. Which of the following are parameters of the equation shown below? rate dph2/dt=kSmgaH+b

All are parameters of the equation.

parameters of the Arrhenius equation k=Ae(-ea/rt)

All choices are parameters of the Arrhenius equation.

What is the physical state of hydrogen chloride at standard temperature and pressure?

Hydrogen chloride is a gas at STP.

Explain the difference between the terms "hydrogen chloride" and "hydrochloric acid". STP, as used below, means standard temperature and pressure.

Hydrogen chloride is a molecular gas at STP. Hydrochloric acid is an aqueous solution of hydrogen chloride.

is true about rate orders?

Rate orders can only be determined experimentally.

Identify which parameters in the following equation are constants and which are variables. Assume that the temperature is constant. rate dph2/dt=kSmgaH+b

Rate, surface area of magnesium, and hydrogen ion concentration all change as the reaction proceeds. Rate orders do not change over the course of the reaction. Rate constants only change if the temperature changes.

Identify the independent variable, the dependent variable, the slope and the y-intercept in the following equation lnk=lnA-ea/r(1/t)

Remember that linear equations have the form y equals m x plus b. The only variable you can control in the laboratory in this instance is the temperature, so T must be the independent variable. The term that independent variable is multiplied by the slope. Therefore, the slope is fraction numerator minus E subscript straight a over denominator R end fraction. ln space A is the y-intercept, because it is associated with the right hand side of the equation. A is also a constant, so it can not be the dependent variable. k is the outcome of the experiment, so it must be the dependent variable.

Which of the following are colligative properties?

Some colligative properties are osmotic pressure, boiling point elevation, freezing point depression, and vapor pressure lowering.

Which of the following would NOT be an appropriate method for extinguishing a magnesium fire?

Water, Carbon dioxide 1. Class D fire extinguishers, clay and sodium carbonate are all appropriate methods to extinguish a magnesium fire. 2. Water is not appropriate. Hydrogen gas would be produced by the reaction of magnesium and water, and hydrogen gas is flammable. A solid water stream can also scatter the fire. 3. Carbon dioxide is not appropriate. Magnesium is capable of using carbon dioxide as a fuel source, producing magnesium oxide and elemental carbon.

Hydrochloric acid is very corrosive. Consult the SDS for hydrochloric acid to determine which of the following are proper precautions for safe handling of hydrochoric acid?

a. Your should not get hydrochloric acid in your eyes. Correctb. You should not get hydrochloric acid on your clothing. Correctc. You should not get hydrochloric acid on your skin. Correctd. You should not breath the hydrochloric acid vapors.

Which colligative property would be best used to model the hydration of chickpeas

Osmotic pressure

LD50 is a measure of a chemical's toxicity. It is, specifically, the dose required to kill 50% of the test population. This information is commonly contained in the SDS (safety data sheet) for a specific chemical. Review the SDS for sodium chloride, and determine the LD50 for the oral administration of sodium chloride to rats.

3 g/kg

How much aqueous 2.3 M NaCl stock must be used to make 500 mL of 2.0 M aqueous NaCl?

435 mL

How many milliliters of concentrated hydrochloric acid must you use to produce 1 .0 L of 1.0 M hydrochloric acid? Concentrated hydrochloric acid is 36% hydrogen chloride by mass and has a density of 1.18 g/mL.

86 mL

What is a colligative property?

Colligative means "bound together". A colligative property is a a property that does not depend in the nature of a chemical species, but on the relative amount of that species in solution.

You will be using magnesium metal in this experiment. Consult the SDS (safety data sheet) for magnesium metal, then select the primary chemical hazard associated with handling magnesium metal.

Magnesium in a flammable metal.

Which is the correct balanced chemical equation for the magnesium-hydrochloric acid reaction?

Mg(s) + 2 HCl(aq) → MgCl2(aq) + H2(g)

best response below regarding the nature of the rate constant.

The rate constant is not a true constant, because it is temperature dependent.

the appropriate safety measure for someone who has had eye contact with hydrochloric acid is the following: Rinse immediately with plenty of water, also under the eyelids, for at least 15 minutes. Obtain medical attention.

True. If someone has eye exposure to hydrochloric acid, then the appropriate safety measure for someone who has had eye contact with hydrochloric acid is to rinse immediately with plenty of water, also under the eyelids, for at least 15 minutes, and to obtain medical attention.