Random 1
In the following oxidation-reduction reactions, what element is oxidized and what element is reduced?
3CoSO4 + 5 KI + KIO3 + 3 H2O --> 3 Co(OH)2 + 3K2SO4 + 3 I2
I- in KI is oxidized and I in IO3- is reduced
Name it:
Na2SO4 • 10H2O
sodium sulfate decahydrate
8Al + 3Fe3O4 → 9Fe + 4Al2O3
In the reaction above, how many moles of Aluminum will produce 1.0 mol of Iron?
8/9 OR 0.89
Provide the correct formula for:
ammonium oxalate
(NH4)2C2O4
A sample of a solid metal has a mass of 23.795 g. When the solid metal is placed in a graduated cylinder that has 55.25 mL of water, the water level rises to 61.00 mL. What is the density of the metal? Answer should be in 3 SF
4.14 g/cm3
Antimony, Sb, has two stable isotopes. Given that 43.8% of natural antimony is Sb-123 with the experimentally determined mass of 122.904 amu, what is the other stable isotope?
Sb-121
Determine the balanced molecular reaction for the following, include states of matter:
Magnesium carbonate solution plus aqueous hydrochloric acid (HCl)
MgCO3(aq) + 2HCl(aq) --> MgCl2(aq) + H2O(l) + CO2(g)
2 MnO4- + 5 H2O2 + 6 H+ --> 2 Mn2+ + 8 H2O + 5 O2
What volume of a 0.150 M KMnO4 solution would be needed to titrate 75.0 mL of a 0.150 M H2O2 solution?
30.0 mL
How many grams of nitric acid, HNO3, can be prepared from the reaction of 138 g of NO2 with 54.0 g H2O according to the equation below?
3NO2 + H2O → 2HNO3 + NO
126 g HNO3
Perform the operation expressing the correct amount of digits:
(3.8095) x (6.02214 X 1023)
_________________________
(39.0983 + 15.9994 + 1.00794)
4.0890 X 1022
When a 16.8-gram sample of an unknown mineral was dissolved in acid, 4.4-grams of CO2 were generated. If the rock contained no carbonate other than MgCO3, what was the percent of MgCO3 by mass in the limestone?
Molar mass (g/mol): MgCO3 = 84 and CO2 = 44
50%
To identify a gas, Mr. Gonzalez carried out the following experiment: He weighed an empty 4.60 L bulb, then filled it with the gas at 1.80 atm and 22.0 °C and weighed it again. The difference in mass was 9.50 g. Identify the gas.
N2
A 100.0 mL sample of acidified dichromate ions of unknown molarity were titrated with a 0.100M solution of iron(II) chloride. If 43.2 mL of iron (II) chloride were used to fully react the dichromate:
What is the molarity of the dichromate ions?
0.00720 M Cr2O72-
Provide the net-ionic equation for:
Sodium sulfide + lead (II) nitrate
S2-(aq) + Pb2+(aq) --> PbS(s)
The MnO4- is often used to analyze for the Fe2+ content of an aqueous solution via the reaction:
MnO4- + Fe2+ --> Fe3+ + Mn2+ (in acidic solution)
A 50.00 mL sample of a solution containing Fe2+ requires 36.43 mL of a 0.025 M KMnO4 solution for complete reaction. The concentration of the Fe2+ in the original solution is:
9.1 X 10-2 M
Ethanoic Acid solution is added to a solution of Sodium Hydrogen Carbonate. include states of matter.
Determine the net ionic equation
HC2H3O2(aq) + HCO3-(aq) 🡪 CO2(g) + H2O(l) + C2H3O2- (aq)
An element X forms both a dichloride (XCl2) and a tetrachloride (XCl4). Treatment of 10.00 g XCl2 with excess chlorine forms 12.55 g XCl4. Calculate the atomic mass of X, and identify X.
207.2 g/mol (Lead)
Uranium naturally exists in the Earth's crust at an average concentration of 4.0 g U / metric ton of a crust. What mass of uranium, in kg could be extracted from the 1500 lbs of the Earth's crust?
2.7 x 10-3 kg U
25.0 mL of 0.250 M KI, 25.0 mL of 0.100 K2SO4, and 15.0 mL of 0.100 M MgCl2 were mixed together in a beaker. What are the molar concentrations of I¯, Cl¯ and K+ in the beaker?
Iodine: 0.0962 M
Chloride: 0.0462 M
Pottasium: 0.173 M
A gas sample is found to be 40.1% sulfur and 59.9% oxygen. In a lab experiment you obtain the following data:
P = 1.00 atm; V = 500.0 mL; T = 298K and the sample had a mass of 1.635g. Determine the molecular formula for the gas.
SO3
Balance the following redox reaction in basic conditions:
Co(OH)3(aq) + Sn(s) ---> Co(OH)2(aq) + HSnO2¯(aq)
OH¯ + 2Co(OH)3 + Sn ---> 2Co(OH)2 + HSnO2¯ + H2O
____NaN3(s) -----> ____Na(s) + ____N2(g)
Assume that 65.1 L of N2 gas are needed to inflate an air bag to the proper size.
a. How many grams of NaN3 must be included in the gas generant to generate this amount of N2? (Hint: the density of N2 gas at this temperature is about 0.916 g/L).
A catalyst is then added to speed up the rxn.
____Na(s) + ____Fe2O3(s) -----> ___Na2O(s) + ___Fe
b. How much Fe2O3 must be added to the gas generant for this amount of NaN3? *think about the connection with Na*
a. 92.2 g NaN3
b. 37.7 g Fe2O3
A sheet of iron with a surface area of 525 cm2 is covered with a coating of rust that has an average thickness of 0.0021 cm. What minimum volume of an HCl solution, in mL, having a density of 1.07 g/mL and consisting of 14% HCl by mass is required to clean the surface of the metal by reacting with the rust? Assume that the rust is Fe2O3(s), that it has a density of 5.2 g/cm3.
52.34 mL
Mercury is highly toxic and often present in small quantities in lake and river water. A sample of water is taken from Lake Waco and found to contain 0.9 µg Hg/cm3. Lake Waco containers 9.7 x 107 m3 of water as of 2017. What is the total mass of Mercury, in kg, present in the lake?
8.7 x 105 kg Hg
The balanced equation for the combustion of octane is shown below:
2C8H18 + 25O2 → 16CO2 + 18H2O
The volume of one cylinder in an automobile is about 0.500L. If the air intake is 45.0°C and 1.00 atm of pressure, calculate the grams of octane that the fuel injection should send to the cylinder to completely react with the O2 in the sample of air. Assume that air is 20.0% oxygen.
0.0350 g