Chem Lab Final

What piece of PPE should be worn at all times in lab?

safety goggles

Which mathematical method most closely fits the temperature data obtained during the water-cooling experiment?

exponential

Volumetric glassware have two different types of volumes, a "nominal" volume and a "true" volume, with the "true" volume being etched or enameled on the vessel.

False

What type of powder was used to enhance the visibility of the oil layer?

lycopodium powder

What is the average deviation from the mean for the following values: 7, 3, 5, 2, 8 ?

sum of the absolute difference between each value and the mean over the mean; 2

What is the volume (in mL) of the oleic acid layer if the mass of the layer is 1.32 X 10 -5 g? (Density = 0.895 g/mL)

1.47 x 10^-5 mL

The density of water changes with temperature.

True

Which test should be used to determine whether an outlying value can be omitted from a given data set?

Q Test

To clean the volumetric pipet after pipetting the dilute oleic acid which of the following should not be used?

Water

What transition metal was contained within the compound analyzed via absorption spectroscopy this semester in experiment 4?

Chromium

The sample container used for measuring solutions via absorption spectroscopy is called a what?

Cuvette

The law used to determine the concentration of unknowns based on their absorbance is which of the following?

Beer's Law

Which two things are indicative of a Bunsen burner flame that is cooler?

Yellow and smoky

What is a casserole?

looks like an open container that could be used to cook a casserole with handle

All crystalline materials have the exact atom ratios predicted by their molecular formulae.

False

A set of standards were analyzed via absorption spectroscopy and plotted using Excel. The best fit trendline gave the equation y = 17.7 x, where y is the absorbance and x is the molar concentration. An unknown solution was subsequently measured and yielded an absorbance of 0.545. What is the molar concentration of the unknown solution?

0.0308 M

A 4.214 g sample of NaHCO3 was heated strongly in a crucible. After three heatings, the mass in the crucible was a constant 2.609 g. What is the percent yield of the reaction? Molar masses: NaHCO 3 = 84.0 g/mol, Na 2CO 3 = 106.0 g/mol, H 2O = 18.0 g/mol, CO 2 = 44.0 g/mol

98.1%

In the reaction of H2 O2 with MnO4-, shown below, MnO4- is reduced to Mn 2+ and H2 O2 is:
2 MnO4- + 5 H2 O2 + 6 H+ → 2 Mn2+ + 5 O2 + 8 H2 O

Oxidized to O2

In the redox titration, MnO4- has an intense purple color but Mn 2+ is colorless. The endpoint of the titration is:

a pale pink color

In the neutralization titration, what is the purpose of potassium hydrogen phthalate (KHP)?

standard

In an acidic solution...

H+ is greater than OH-, and pH<7

Hess' Law of Heat Summation is a direct consequence of which law of thermodynamics?

First: energy within an isolated system is conserved

To determine the limiting reagent in the Hess' Law experiment, moles of each reactant were determined and compared. A student mixes 50.0 mL of 1.01 M NaOH and 50.0 mL of 1.00 M HCl in a thermos to form H2 O. What is the limiting reagent?

HCl

When a sample of NH4 NO3 was dissolved in water, the temperature decreased by 1.9 °C. The reaction is:

endothermic and absorbed heat

A solution of NaOH was standardized via titration of 1.75 g of KHP (MM = 204.22 g/mol).The total volume of NaOH (MM = 40 g/mol) used to titrate the sample was 38.30 mL, whatis the molarity of the NaOH solution?
NaOH + KHP → NaKP + H2 O

0.224 M

From the balanced equation above, 1 mole MnO4- reacts with 5 moles Fe2+. You weighed 0.427 g Fe(NH4 )2 (SO4 )2 ·6H2 O for the titration and, using its molecular weight, determined that it contained 1.09 x 10-3 moles Fe2+. How many moles of MnO4- are required to reach the equivalence point in the redox titration?

2.18 x 10^-4

Which law states that "If two elements combine to form more than one compound, then the amounts of element A that combine with a fixed amount of element B will be in a ratio of small whole numbers?"

Law of Multiple Proportions

According to Boyle's law, as volume (V) decreases, pressure (P) increases. A graph of 1/P on the x-axis and V on the y-axis should...

be linear and regress to zero

Particles in the gas state...

are far apart and travel at high velocities

Charles' Law states that the volume of a fixed amount of gas is directly proportional to what unit of temperature?

Kelvin

The molar volume of what two gases were determined in the molar volume of a gas experiment?

Hydrogen and Oxygen

Molecules at absolute zero theoretically have no thermal energy and are therefore without linear motion.

True

A gas mixture containing 44.0 g of CO2 (MW = 44.0 g/mol) and 18.0 grams of H2O(MW = 18.0 g/mol) is held at a constant temperature and pressure of 0°C and 1 atm respectively. How many liters of gas are present in the gas mixture?

44.8 L; two moles of gas total so 22.4 x 2

A gas that has a pressure of 1.0 atm and volume of 45 mL at 25°C is heated to 78°C. If the pressure remains constant, what is the final volume of the gas?

greater than 45 mL

A gas that has a pressure of 1.0 atm and a volume of 45 mL will have what new volume when the pressure is increased to 5.0 atm?

9.0 mL