Atomic Structure and Properties
Molecular and Ionic Compounds
Intermolecular Forces and Properties
Chemical Reactions
100
A student has a 1g sample of each of the following compounds: NaCl, KBr, and KCl. This is the ranking of these samples from least to greatest number of moles.
What is KBr, KCl, NaCl
100
The elements C and Se have the same electronegativity value, 2.55. What can you conclude about the compound that forms between C and Se?
It is nonpolar covalent
100
A 1L sample of helium gas at 25°C and 1atm is combined with a 1L sample of neon gas at 25°C and 1atm. The temperature is kept constant. What can you say about the average kinetic energy of the gasses before and after they are mixed?
The average kinetic energy of the helium and neon gasses do not change when they are combined
100
Classify the following chemical reaction:
Single Replacement
200
The ground state electron configuration of the F- ion
What is 1s22s22p6?
200
The particulate model above represents an ionic solid. Will this solid conduct electricity? Why or why not?
No, because the ions cannot move freely within the crystal lattice structure of the solid
200
The lewis dot structure for Methane, CH4, is shown above. What intermolecular forces are present in methane?
London Dispersion Forces (LDFs)
200
Two aqueous solutions are mixed together. What must be true for a double replacement reaction to occur?
One of the products must be insoluble in water
300
This helps to explain why the electron affinity of Br has a greater magnitude than that of I
What is a greater coulombic attraction between an added electron and the nucleus in Br than in I?
300
A sample of N2H4 has a mass of 25g. Identify the numerical quantity that is needed to convert the number of grams of N2H4 to the number of moles of N2H4
molar mass (32 g/mol)
300
Why does NH3(l) boil at −28°C, whereas PH3(l) boils at −126°C?
NH3 contains hydrogen bonds that require more energy to overcome than the dipole-dipole forces in PH3
300
A student made observations related to the contents of an Erlenmeyer flask during a titration of HCl with NaOH. Identify an observation that could have led the student to conclude that a chemical change took place during the titration.
Indicator changed color
OR
Solution becomes warm
400
Li forms the compound Li2O, which is an ionic compound that is brittle. Identify another element, M, that is likely to form a brittle, ionic compound with the formula M2O. Justify your answer in terms of periodic trends.
What is Na, K, Rb, Cs, or Fr? (same number of valence electrons)
400
A particle-level diagram of a metallic element is shown above. Typically, metals are both malleable and ductile. Explain these properties in terms of electrons in a metallic bond.
Electrons are equally shared among all atoms of the element (bonds are nondirectional)
400
A solution of cobalt (II) chloride was prepared by dissolving 2.60g of CoCl2 (molar mass 130.g/mol) in enough water to make 100.mL of solution. What is the molar concentration of the solution?
0.200 M
400
Complete and balance the following reaction:
C4H10 + O2 →
2 C4H10 + 13 O2 → 8 CO2 + 10 H2O
500
Potassium forms two oxides, K2O and K2O2. A chemist can determine the mass of K in a sample of known mass that consists of either pure K2O or pure K2O2. From this information, can the chemist know which compound is in the sample? Explain.
Yes, because the percent mass of K in the compound can also be determined
500
Draw a complete Lewis electron-dot diagram for the C2Cl4 molecule.
500
A wavelength of 510nm corresponds to an approximate frequency of 6×1014s−1. What is the approximate energy of one photon of this light?
4x10-19 J
500
What is the net ionic equation for the reaction between aqueous sodium fluoride and hydrochloric acid?
F-(aq) + H+(aq) → HF(aq)