chem 115 final
6.7003 - 6.92 = ___
-0.22
Express the number -3.45 in appropriate scientific notation
-3.45 x 10^0
What is the change in temperature if an object goes from 273 K to 243 K?
-30 K
3.2 g + 0.6565 kg = ___ kg
0.6597
The density table in the lab manual says that the density of water at 19 °C is 0.998405 g/mL and at 20 °C is 0.998203 g/mL. What is the density at 19.1 °C?
0.998385 g/mL
In the decomposition reaction of heating magnesium hydroxide to produce water vapor and magnesium oxide, what are the coefficients of the balanced equation, written as stated?
1, 1, 1
How much of solid KIO do you need to make 25.00mL of a 0.20M Potassium Iodate solution?
1.07 g
Evaluate the following: 2.3456 - 1.2
1.1E0
Evaluate: 5260 + 20.56 + 7389 + 2.493 (assume 5260 has three sig figs).
1.267E4
(1.2E4) + 3.021 =
1.2E4
3.1415 x 542 x 8.314 = ___
1.42 x 10^4
Evaluate the following: 2.0 x 0.678
1.4E0
To make 100.0 mL of a solution that is 0.15 M in malonic acid and 0.20 M in manganese sulfate monohydrate requires ____ g of CH(COOH) (molar mass = 104.0615 g/mol) and ____ g MnSO⋅HO (molar mass = 169.02 g/mol).
1.6; 3.4
What is the maximum correct percent yield in any reaction?
100%
Which piece of glassware would be most appropriate for simply holding (or containing) about 75 mL of a solution when accuracy is not important?
100-mL beaker
Which piece of glassware would be most appropriate to use to make 100 mL of a solution of a certain concentration?
100-mL volumetric flask
A 12.5% (w/v) solution means you have __ of NaOH per 1L of solution.
125 g
A solution is made by mixing 15 g of alcohol with 85 mL of water (assume the density of water is 1.0000 g / mL). What is the percentage of alcohol in the resulting solution?
15%
Assume that you started with 0.297g of magnesium and obtained 0.493 g of the dry oxide at the end. What is the molar ratio of magnesium to oxygen in your product?
1:1
In the reaction of solid magnesium with atmospheric oxygen to produce solid magnesium oxide, what are the coefficients of the balanced equation, written as stated?
2, 1, 2
What is the value of the Rydberg constant for hydrogen, in units of Joules?
2.18 x 10 J
Round off 23.64 to three sig figs.
2.36E1
Calculate the number of water molecules present in a sample of unknown Epsom Salt given the following data: A 2.0000 g sample is heated until the crystals are reduced to a dry powder. After cooling, the mass of the residue if 1.2500 g.
2.51 x 10 molecules
Evaluate the following: (1.20 x 104) x 23
2.9E3
Your lab practical (aka FINAL EXAM) grade will be worth what percentage of your final average in this course?
20%
Which piece of glassware would be most appropriate for transferring exactly 25.00 mL of a solution from one container to another?
25-mL volumetric or graduated pipet
Which piece of glassware would be most appropriate for measuring out 250 mL of a solution
250-mL graduated cylinder
8000^(1/3) =
2E1
What is the volume, in cubic inches, of a packing box if its dimensions are 40 inches long, 30 inches wide, and 20 inches high?
2E4
How many sig figs are in the following measurement: 0.000987 m ?
3
If you produce the reactant solutions correctly in this lab procedure, how many colors should the resulting solution cycle through?
3
In the reaction of solid magnesium with atmospheric nitrogen to produce solid magnesium nitride, what are the coefficients of the balanced equation, written as stated?
3, 1, 1
In making a 3% (w/v) solution of boiled starch, how many grams of starch would you add to 100 mL of boiling water?
3.0
Perform the following calculation: 6.5 + 23.546 =
3.00E1
If 3.48g of copper is recovered at the end of this experiment after allowing 4.00g of copper to react with nitric acid in reaction #1, what is the theoretical yield and the actual percent yield of the reaction?
4.00 g and 87%
To make 100.0 mL of a solution that is 0.20 M in potassium iodate using 0.080 M sulfuric acid as the solvent requires ___ g of KIO (molar mass = 214.001 g/mol).
4.3
If the directions in the lab manual told you to weigh out about 4.50 g of a chemical, but the balance reads: 4.502 g. What would you record in your data table?
4.502
Find "s" if: 112 s^12 = 2.65 x 10^10
4.99E0
Calculate the wavelength of a photon emitted during the relaxation of an electron from the n=6 to n=2 energy level.
410
Calculate the wavelength of a photon emitted during the relaxation of an electron from the n=5 to n=2 energy level.
434
Calculate the wavelength of a photon emitted during the relaxation of an electron from the n=4 to n=2 energy level.
486
What is the wavelength that corresponds to a frequency of 6.00 x 10 Hz?
5 x 10 m
Convert 236°C to Kelvin using the following formula: K = °C + 273.15.
5.09E2
Round 54.68 to three sig figs.
5.47E1
Round 549.65 to three sig figs.
5.50E2
You need 2.0 L of a 3.0 M solution of hydrochloric acid, HCl, in an experiment, but there is just 12.0 M HCl solution in stock. How much stock solution do you need to dilute to 2.0 L to end up with this?
500 mL
Given a stock solution of 30% (w/w) hydrogen peroxide, how much solution, in mL, would you need to start with if you were asked to make 100.0 mL of a 5.0 M hydrogen peroxide solution? (hint: the molar mass of hydrogen peroxide is 34.016 g/mol, and the density of the peroxide solution is 1.11 g/mL)
51
How many sig figs are in the following measurement: 54.3158 m ?
6
In the reaction of water with the by-product magnesium nitride to produce ammonia and magnesium hydroxide, what are the coefficients of the balanced equation, written as stated?
6, 1, 2, 3
Round 64,400 to four sig figs.
6.440E4
What is the correct measurement to record in your data if the digital readout on the balance won't stop jumping from "64.382" to "64.381"?
64.381 64.382
emitted during the relaxation of an electron from the n=3 to n=2 energy level.
656
A certain magnesium sulfate salt hydrate sample has a mass of 246.506 mg. After heating and cooling it the sample has a mass of 120.366 mg. How many moles of water were included in 1 mole of the original salt's ionic lattice structure?
7
Convert 7894 g into kg
7.894 kg
Convert 0.00850 L into µL
8.50 x 10E3 µL
Which one of the following would you use to separate sand from iron fillings?
A bar magnet
You should always handle the crucible and its cover with tongs. What happens if you handle the cruicible and cover with your fingers?
All of the other answers are correct
When ever you are using an unknown chemical in the lab, you have to search for the chemical's...
All the other choices are true
Several experiments will require you to work with an unknown chemical that will have a code written on the container. The code must be entered on the post-lab assignment pages that you submit to your TA in order for the TA to know how to grade your paper. If you do not include the unknown code on your assignment, what is the consequence?
Automatic grade of zero on the entire assignment.
An 89.7 is equivalent to what letter grade in General Chemistry lab?
B
Red, green and blue light has wavelength's 650 nm, 490 nm, and 430 nm. Write the order of decreasing frequency of light.
Blue > Green > Red
Which of the following mixtures could NOT be separated into its components by decanting?
Coffee in hot water
Pouring off a solvent and leaving a precipitate behind is called ___.
Decantation
If I pour the water off after I boil the potatoes, what is this an example of? (I am separating the solid potatoes from the liquid hot water)
Decanting
Which of these are methods of separating a solid from a liquid?
Decanting, filtering and evaporating
Why does the graduated cylinder have to be clean and dry before every trial? Choose the best answer.
Even a few extra drops of water in the beginning could make the density calculations be in error later in the procedure.
Determine if the following sentence is True or False. SO has been proven to be toxic and carcinogenic to humans?
False
If you have a question about the grading of one of your returned papers, you must ask your TA that question BY the day after you receive the graded paper. After that, the grade will not be changed.
False
It is allowable for you to drop the lecture part of the class and keep taking the lab if dropping the lab would then take you below full-time student status.
False
The last digit on a digital balance is too uncertain to record, so it is usually left off of the recorded measurement.
False
In the process of evaporation, which one of the following pieces of laboratory apparatus would NOT be used?
Filter funnel
Sodium chloride can be separated from rocks by first adding water to the mixture to dissolve the sodium chloride. The separation then takes place in two stages:
Filtration followed by evaporation
Which of the following is NOT a physical property?
Flammability
What is the purpose of adding water during the experimental procedure?
For hydrolysis of magnesium nitride
Why will the crucible and its contents gain mass when heated?
Formation of magnesium oxide and magnesium nitride
Calibration of any particular spectroscope is best done by using a _____ gas discharge bulb
Helium
What kind of goggles are you required to wear while in the laboratory?
Indirectly- or Non-vented
Where we can find the unique identification code for each chemical
MSDS
What does the abbreviation of MSDS stand for?
Material Safety Data Sheet
What is the empirical formula for Magnesium Oxide?
MgO
A certain magnesium sulfate salt hydrate sample has a mass of 246.506 mg. After heating and cooling it the sample has a mass of 120.366 mg. What is the chemical formula of the dehydrated salt
MgSO4
In this experiment, you are to remove the water molecules from the crystal lattice of a magnesium salt, creating an anhydrous form of the chemical. The molecular formula for the anhydrous form of Epsom Salt is:
MgSo4
A certain magnesium sulfate salt hydrate sample has a mass of 246.506 mg. After heating and cooling it the sample has a mass of 120.366 mg. What was the chemical formula of the original sample?
MgSo4•7H2O
Two or more substances mingled together, but not chemically combined are known as a _____
Mixture
Magnesium emits radiation at 285nm. Could we detect this spectrum with the spectroscope and the naked eye?
No
Pick the item that is not needed during this experiment
Oxide strip
For the formula PV = nRT, rearrange it to solve for n. n = ?
PV / RT
What does it mean, in terms of temperature, if a reaction is exothermic?
Reaction releases heat and feel hot to touch
In this experiment, you are exposed to reactions like:
Redox and metathesis
When preparing a pipet or buret for use, what is the accepted protocol? Choose the best answer.
Rinse the buret/pipet with a small amount of water three times, then rinse the buret/pipet with a small amount of the solution to be measured three times.
Why must you use the same balance each time you make a measurement? Choose the best answer.
So any error in the balance will be systematic and cancel itself out.
The use of prism in the spectroscope is for _____
Splitting the light
What is the proper chemical name of SO3?
Sulfur Trioxide
In the MSDS for Epsom Salt, it is mentioned that thermal decomposition leads to toxic gases. This is also mentioned in the lab manual. What is the gas?
Sulfur trioxide
A student ended up getting 150% yield. What is most likely the reason?
The other three are all good possibilities
The abbreviation "TD", as applied to chemical glassware, means __________.
To Deliver
The abbreviation "TC", as applied to chemical glassware, means __________.
To contain
After getting to class and listening to the TA's pre-lab lecture, you should include in your lab notebook any changes to the procedure or chemicals made by the TA.
True
Another student in your lab section made a mess on the balance and then walked away and left it. T or F - you could get points deducted from your post-lab assignment because of this??
True
Being disruptive in class, sitting on the benches, arguing, texting, making phone calls, or otherwise NOT BEING ON TASK will most likely result in your being asked to leave the lab for the day and to take a zero for the days work for disruptive behavior.
True
It is allowable to drop the lab portion of General Chemistry I (CHEM 115 or CHEM 116) and stay enrolled in the lecture portion (CHEM 105 or CHEM 106) if you want or need to. You can always take the lab later
True
Malonic acid is a strong irritant AND a corrosive. True or False?
True
When lighting a Bunsen burner, the gas supply valve on the bench should be all the way open and the one on the burner should be used to regulate the flame, True or False?
True
You lab notebook should include a Table of Contents (TOC) for about the first three pages. After making the TOC you should consecutively number the notebook's pages with a pen.
True
What liquid is usually used to calibrate a thermometer?
Water
The crucible and crucible lid are both weighed together. If the lid breaks apart in the middle of the experiment, do we have to start the experiment again?
Yes, we have to start again
Balances that read out to 3 or more decimal places are called ___________.
analytical balances
What was (or what SHOULD have been) the color changes you saw in lab when the three solution were mixed?
clear --> amber --> dark blue --> clear
After adding the sulfuric acid and letting that reaction proceed to completion, what chemical species were left in the beaker?
copper(II) sulfate and water
The lab notebook should be filled out BEFORE you come to lab. Of the following choices, choose the ONE thing that does NOT have to be in your notebook at the beginning of the lab period.
data from the experiment
In your notebook it is permissible to write with: (select the BEST answer).
highlighters as emphasis and on drawings colored pens as emphasis and on drawings but not as the main writing color black pen blue pen
If you make a mistake in your lab notebook:
line through it with a single pen line and initial the line
For the formula PV = nRT, rearrange it to solve for V. V = ?
nRT / P
In step 2, when you added nitric acid to the copper wire, what gas was produced?
nitrogen dioxide
The photon emitted during the relaxation of a hydrogen atom's electron from the n=3 to n=2 energy level produces a ____ color line on the emission spectrum.
red
What type of reaction is the digestion of solid copper wire by nitric acid?
redox
What is the purpose of the crucible lid in this experimental procedure?
to control the rate of the magnesium combustion reaction
Failure to be wearing long pants, closed-toe shoes, and goggles when in the laboratory will most like result in your being asked to leave for the day and to take a zero for the days assignments due to safety violations.
true
The photon emitted during the relaxation of a hydrogen atom's electron from the n=6 to n=2 energy level produces a ___ color line on the emission spectrum.
violet
