Atoms/PT/Nuclear
Explain the similarities and differences in atomic structure of Al-26 and Al-27.
Same p (13) and e (13). Different numbers of n (Al-26 has 13 n, Al-27 has 14 n).
Write the formula for dinitrogen trisulfide
N2S3
Predict the products & BALANCE
Cs + AlCl3 -->
3 Cs + AlCl3 --> 3 CsCl + Al
Draw a particle diagram that represents an element in the gaseous state.
Particles should be drawn far apart.
How many grams of NaCl are needed to make 300 g of a 6.8 ppm solution?
0.00204 g of NaCl
ppm = part/whole x 1,000,000
6.8 = part/300 x 1,000,000
part = 0.00204 g
Magnesium is used in fireworks to create explosive reactions that release light. Name 2 other elements that should have similar reactivity as Mg.
Be, Ca, Sr, Ba, or Ra are the possible options
Fe3(PO4)2
Predict the products & BALANCE:
HNO3 + Ca -->
2 HNO3 + Ca --> Ca(NO3)2 + H2
Draw a particle diagram that shows a physical change versus a chemical change. Be sure to label each.
Answers will vary
Which solution would have the lowest freezing point: NaNO3, AlCl3, HCl, or C3H6?
AlCl3
More particles in solution = bigger change in freezing point and boiling point. AlCl3 has 4 particles because it breaks into aluminum and chlorine ions in water. Note that C3H6 is covalent so it only counts as one particle as it will not break into ions in solution
How many protons, neutrons, and electrons are in a Ca-41 ION?
P = 20
N = 21
E = 18 (because +2 charge)
State two general properties that a compound like Na2O would have.
high melting or boiling point, soluble in water, conductive in solution, hard
Predict the products and BALANCE:
H3PO4 + NaOH -->
H3PO4 + 3 NaOH --> Na3PO4 + 3 H2O
The gas pressure in an whipped cream can is 1.5 atm and 295 K. Assuming that the volume of the gas stays constant, what is the pressure in the can if the temperature is raised to 350 K?
1.78 atm
P1/T1 = P2/T2
1.5/295 = P2/350
P2 = 1.78 atm
What is the concentration of HNO3 if 25 mL of it is neutralized by titrating it with 30 mL of 0.3 M Al(OH)3?
1.08 M
MaVa = MbVb
Ma x 25 = (0.3 x 3) x 30
Ma = 1.08 M
Multiply the base side by 3 because Al(OH)3 gives off 3 OH's
If you have 200 g of Kr-85, how long will it take for only 6.25 g to remain?
53.65 years
200 --> 100 --> 50 --> 25 --> 12.5 --> 6.25
5 half lives * 10.73 yr = 53.65 years
Explain, in terms of subatomic particles, the difference between ionic and covalent bonds.
Ionic = transfer of electrons
Covalent = sharing electrons
Predict the products and BALANCE:
AgNO3 + MgSO4 -->
2 AgNO3 + MgSO4 --> Ag2SO4 + Mg(NO3)2
How much energy is absorbed when 3.8 moles of NO2 is synthesized?
126.16 kJ
From reference table 66.4 kJ to make 2 moles. So 66.4 / 2 = 33.1 kJ for 1 mole. 33.1 x 3.8 moles = 126.16 kJ
Sketch a potential energy diagram for the dissolving of ammonium chloride. State whether this process is exothermic or endothermic. State whether this process is a physical or chemical change.
diagram should have products higher than reactants
Endothermic because delta H is positive.
Physical change. The ions are just separating, not changing bonding. Can get the NH4Cl back through physical means (evaporation)
Write the decay equation for U-233.
23392 U --> 42He + 22990Th
Draw the Lewis structures for NCl3 , HF, and CO2. State whether each is polar or nonpolar and circle the one that would have the strongest intermolecular forces.
NCl3 = polar (asymmetrical)
HF = polar (asymmetrical)
CO2 = nonpolar (symmetrical)
HF has the strongest intermolecular forces because it is the most polar since greatest difference in electronegativity between H and F (can do hydrogen bonding)
Predict the products & BALANCE
H2SO4 + Al(OH)3 -->
3 H2SO4 + 2 Al(OH)3 --> 6 H2O + Al2(SO4)3
Draw a heating curve of a pure substance that has a melting point of 10 C and a boiling point of 70 C as it goes from solid to liquid to gas. Label each segment with the states of matter. Circle the part of the graph where the atoms have the highest kinetic energy.
Positive slope, flat at 10 C, positive slope, flat at 70 C, positive slope. s, s & l, l, l & g, g. Highest KE will be at the highest temperature
You have a solution with a pH of 5. You then add NaOH to it and the hydrogen ion concentration decreases 10,000 times. What is the new pH? What color would the solution be if you added thymol blue?
pH = 9
10,000 = 104 so pH changes by 4 units. Since H+ concentration decreases, or base is added, the pH will increase (become more basic).
It would be green with thymol blue because it is in the transition range between yellow (<8) and blue (>9.6).