UNIT 2
The electron configuration of Mg2+ ion is..
What is....1s2, 2s2, 2p6?
The Lewis dot structure, Molecular Geometry, Pi and Sigma Bonds, Hybridization, IMF, and Polarity of BCl3 is..
WHAT IS...
Trigonal Planar
Pi: 0
Sigma: 3
sp2
LDF
Non-Polar
Net ionic for....
AgNO3 + NaCl ----> NaNO3 + AgCl
Ag+ (aq) + Cl- (aq) ----> AgCl (s)
A 15.67 g sample of a hydrate of magnesium carbonate was heated, without decomposing the carbonate, to drive off the water. The mass was reduced to 7.58 g. What is the formula of the hydrate?
MgCO3 . 5H2O
What is the balancing order in a combustion reaction
CHO
The atomic radius of Li is larger than B
What is....Li has less protons so it would have less Zeff, therefore increasing the radius and lowering the coulombic attraction
Cl2 has a BP of 138K while Br2 has a BP of 200K, why?
Even though they both have LDFs, Cl2 has a bigger radius so it has a more polarizable electron cloud, making the forces harder to break resulting in a larger BP
An ion containing oxygen and nitrogen is 34% oxygen by mass. What is the empirical formula?
N20
An unknown compound contains only carbon, hydrogen, and nitrogen. A 0.200 g sample of this compound undergoes complete combustion, producing 0.293 g of carbon dioxide (CO₂) and 0.180 g of water (H₂O). Determine the empirical formula of the unknown compound.
CH3N
In our hydrate lab, why would you remeasure the mass of the anhydrate?
You would remeasure the mass until it is a constant mass to make sure all the water is evaporated from the salt.
here are the ionization energies of an unknown element W. What would be the empirical formula of a compound of W and Cl
1st ionization nrg: 300 kJ/mol
2nd ionization nrg: 500 kJ/mol
3rd ionization nrg: 1060 kJ/mol
4th ionization nrg: 1336 kJ/mol
WCl2
CsCl2 has a higher BP and MP than CO2 as solids. Why?
What is...
CsCl2 is an ionic lattice while CO2 is a molecular compound, so the forces of the ionic lattice is stronger than a molecular compound, making the forces harder to break
How many grams of CO2 will be produced from 15.0g of CH4 and 114g of O2? What is the limiting reactant? How much of the excess reactant remains?
1. 41.1g
2. CH4
3. 59.8g
M₂+ is an unknown metal cation with a 2+ charge. A student dissolves the sulfate of the unknown metal, MSO4, in enough water to make 150.0 mL of solution. The student then mixes the solution with excess barium chloride solution (BaCl2), causing BaSO4 to precipitate. The student collects the precipitate by filtration, dries it, and records the data shown below.
Mass of unknown sulfate, MSO4 = 1.25 g
Mass of filter paper = 0.90 g
Mass of filter paper plus BaSO4 precipitate (1st weighing) = 2.74 g
Mass of filter paper plus BaSO4 precipitate (2nd weighing) = 2.69 g
Mass of filter paper plus BaSO4 precipitate (3rd weighing) = 2.68 g
The student had the cation narrowed down to zinc or strontium. What is the identity of the metal sulfate?
ZnSO4
How would you make a 100.0 mL of 1.0 HCl w/ 6.0 HCl (dilution). Include safety neccessities.
Put on goggles, gloves, an apron, and grab 16.67 mL of 6.0M HCl in the fumehood. Then add roughly 83 mL of distilled water in your 100.0 mL volumetric flask. After you add the water, you add your acid to the water slowly. After the heat regulates, you add distilled water to the mark on the volumetric flask.
The effective nuclear charge experienced by the outermost electron of Na is different than the effective nuclear charge experienced by the outermost electron of Ne. This difference best accounts for which of the following?
What is.. Na has a lower first ionization energy than Ne.
NaCl vs. MgO -Which has a higher melting point?
MgO, because Mg has a 2+ charge while Na has a 1+ charge, therefore there would be more electrostatic attraction
M+ is an unknown metal cation with a 1+ charge. A student dissolves the chloride of the unknown metal, MCl, in enough water to make 100.0 mL of solution. The student then mixes the solution with excess AgNO3 solution causing AgCl to precipitate. The student collects the precipitate by filtration, dries it, and records the data shown below. (The molar mass of AgCl is 143.32 g/mol.)
Mass of unknown chloride, MCl = 0.84g
Mass of filter paper = 0.80g
Mass of filter paper plus AgCl precipitate 1st weighing = 2.66g
Mass of filter paper plus AgCl precipitate 2nd weighing = 2.41g
Mass of filter paper plus AgCl precipitate 3rd weighing = 2.40g
The student narrowed it down to Na or K, what is the identity of the metal chloride?
KCl
An unknown sample in the laboratory contains sodium chloride, NaCl. To determine the percentage of NaCl in the unknown, the sample was dissolved in 50.0 mL of distilled water. The sample was then added to an excess silver nitrate, AgNO3, solution to form a precipitate. The precipitate was then filtered, washed, and dried to a constant mass. Using the information below, calculate the percentage of NaCl in the unknown sample. Mass of unknown sample 1.453 grams Mass of dry filter paper 0.862 grams Mass of precipitate and filter paper after 1st drying 3.565 grams Mass of precipitate and filter paper after 2nd drying 3.081 grams Mass of precipitate and filter paper after 3rd drying 3.082 grams
(a) Write a balanced net-ionic chemical reaction for the formation of the precipitate above.
(b) Calculate the mass of the precipitate.
(c) Calculate the moles of the precipitate. (d) Determine the moles of the sodium chloride in the unknown sample.
(e) Calculate the mass of the sodium chloride in the unknown sample.
(f) Calculate the percentage of sodium chloride in the unknown sample.
a) Ag+ (aq) + Cl- (aq) ---> AgCl (s)
b) 2.22 g AgCl
c) 0.0155 moles AgCl
d) 0.0155 moles NaCl
e) 0.9052g NaCl
f) 62%
What bonds/forces break in a phase change of water?
h-bonds