Chem Mid-term
A 50.0 mg sample of calcium bromide, CaBr₂,(molar mass 200.g) is dissolved in enough water to produce 200.mL of a solution. What is the molarity of calcium bromide in a 50. mL sample of this solution?
.00125M
What is the approximate bond length between the two atoms?
.140nm
An aqueous solution contains 0.6 mol KCl and 1.20 mol NH₄Cl. What is the minimum number of moles of Pb(NO₃)₂ that must be added to the precipitate all of the chloride ions?
0.90mol
__H⁺ + __NO₃⁻ + __ Mg → __ Mg²⁺ + __ NH₄⁺ + __ H₂O When the equation above is balanced with the lowest whole number coefficients, the coefficient for H⁺ is:
10
How many electrons appear in the following half-reaction when it is balanced? 12H⁺ + 2IO₃⁻ → I₂ + 6H₂O
10e⁻ on the left
Which electron configuration represents an atom in an excited state?
1s __ 2s ↑_
Copper(II) sulfate pentahydrate, CuSO4·5H2O(molar mass:250g/mol) can be dehydrated by repeated heating in a crucible. Which value is closest to the percentage mass of water lost from the total mass of salt in the crucibles when the crucible undergoes repetitive heatings until a constant mass is reached?
26%
Predict the balanced products of the following reaction: Chlorine gas is bubbled through a solution of potassium bromide.
2KCl + Br₂
What is the bond energy(bond strength) of the bond?
330J
A 2L sample of N₂ and a 6L sample of Ar, each originally at 1 atm and 0 Celsius, are combined in a 2L tank. If the temperature is held constant, what is the total pressure in the 2L tank?
4atm
A measured mass of an unreactive metal was dropped into a small graduated cylinder half filled with water. The following measurements were made. Mass of metal = 19.611 grams Volume of water before addition of metal = 12.4 milliliters Volume of water after addition of metal = 14.9 milliliters The density of the metal should be reported as:
7.84 grams per mL
The first five ionization energies of a second-period element are listed in the table below. Which of the following correctly identifies the element and best explains the data in the table?
B, because it has five valence electrons
Which of the following is LEAST soluble in water?
BaCO₃
Which of the following molecules has a dipole moment of zero?
CF₄
Which gas listed below has an average atomic or molecular speed closest to that of N₂ molecules at 0 Celsius and 1 atm?
CO
The unbalanced products of the combustion of scurose (C₁₂H₂₂O₁₁) are...
CO₂ and H₂O
In which of the following compounds is the mass ratio of chromium to oxygen closest to 1.6 to 1.0?
CrO₂
Which of the following correctly lists the compounds in order of increasing lattice energy?
CsI < KCl < CaO < MgO
Styrene, a compound used to make Styrofoam cups(MM = 104g/mol) contains 92.3%C and 7.75%H. What is styrene's molecular formula?
C₈H₈
Which of the following has the bonds arranged in order of decreasing polarity?
H- F > N-F > F-F
A strong aside is added to a strong base. What is the net ionic equation of the reaction?
H⁺(aq) + OH⁻(aq) → H₂O(l)
The potential energy as a function of internuclear distance for three diatomic molecules, X₂, Y₂, and Z₂, is shown in the graph to the right. Based on the data in the graph, which of the following correctly identifies the diatomic molecules, X₂, Y₂, and Z₂?
H₂ N₂ O₂
Equal masses of three different ideal gases, X, Y, and Z, are mixed in a sealed rigid container. If the temperature of the system remains constant, which of the following statements about the partial pressure of gas X is correct?
It depends on the molecular masses of X,Y, and Z.
The atoms of an element, X, has the electron configuration below. What compound would element X most likely form with magnesium(Mg)? X: 1s²2s²2p⁶3s²3p³
Mg₃X₂
2H₂O + 4MnO₄⁻ + 3ClO₂⁻ → 4MnO₂ + 3ClO₄⁻ + 4OH⁻ Which compound in the reaction above contains the element that is reduced?
MnO₄⁻
The element in the photoelectron spectroscopy graph, below, is most likely
N
The diagram above represents the absorption spectrum for a pure molecular substance. Which of the following correctly indicates the type of transition observed for the substance in each of the regions of the absorption spectrum?
Region X: electron transition Region Y: molecular vibration Region Z: molecular rotation
In which of the following species does sulfur have the same oxidation number as it does in H₂SO₄?
SO₂Cl₂
What is the molecular geometry of BrI₃
T-shaped
What is the electron geometry of H₂O?
Tetrahedral
The boiling points of the elements helium, neon, argon, krypton, and xenon increase in that order. Choose all of the following statements that best account for this increase?
The (London) dispersion forces increase
Two flexible containers for gasses are at the same temperature and pressure. One holds 0.50 gram of hydrogen and the other holds 8.0 grams of oxygen. Which of the following statements regarding these gas samples is FALSE?
The average speed of the hydrogen molecules is the same as the average speed of the oxygen molecules.
When 100ml of 1,0 M AlCl₃ is mixed with 100ml of 1.0M Na₂CrO₄, a yellow precipitate forms and [CrO₄²⁻] becomes negligibly small. Which of the following is a correct listing of the ions remaining in solution in order of increasing concentration?
[Al³⁺] < [Na⁺] < [ Cl⁻]
The table below shows the structural formulas and molar masses for three compounds. Which of the following is a lost of the compounds in order of increasing boiling points?
butane < acetone < 1-propanol
What is the hybridization of one of the carbon atoms in C₂H₄?
sp²
