DAT – Chemistry Written Exam Questions Correctly Answered.
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DAT – Chemistry Written Exam Questions Correctly Answered.
For the reaction below, which of the following sets of coefficients would balance the reaction?
__HNO3 + __S → __H2SO4 + __NO2 + __H2O - CORRECT ANSWER 6,1,1,6,2
Which of the following interactions is the strongest? - CORRECT A...
Which of the following interactions is the strongest? - CORRECT ANSWER Ionic Bonds
What is the maximum number of electrons that the d-subshell can hold? - CORRECT ANSWER 10
Calcium chromate (CaCrO4) is a yellow solid with a Ksp of 7.1 x 10-4. Determine the ion product
constant and whether a precipitate would form when an aqueous solution contains 26 mM of Ca2+ and
29 mM of CrO42-. - CORRECT ANSWER B.IP = 7.54 x 10-4; yes, precipitation will occur
STEP 1: To determine determine the ion product (IP) constant, we must first write out the reaction and
its ion product (IP) equation:
CaCrO4 (s) → Ca2+ (aq) + CrO42-(aq)
IP = [Ca2+][CrO42-]
STEP 2: Next, we can substitute the concentrations of Ca2+ and CrO42- into the formula above.
Note: The unit conversion of 1 mM = 0.001 M.
IP = [0.026 M Ca2+][0.029 M CrO42-]
IP = 0.000754 = 7.54 x 10-4.
STEP 3: Lastly, to determine whether a precipitate will form, we have to compare ion product constant
to the given Ksp value. Since IP > Ksp, the reaction is considered saturated and will shift to the left.
Therefore, a precipitate will form.
A container holds 4.0L of gas at 3.5 atmospheres and a temperature of 27oC. If the pressure is reduced
to 0.8 atmospheres without a change in temperature, what would be the volume of the gas? - CORRECT
ANSWER 18.0L
P1V1=P2V2
(4)(3.5) = (0.8)(V2)
,V2 = 14/0.8
= 17.5L or 18.0L
A NaOH solution has a molarity of 2.00 M and is titrated with 75.0 mL of 0.500 M H2SO4. What volume
of NaOH is needed to reach the end point? - CORRECT ANSWER B. 0.03750 L
What is the bond angle that exists within a molecule of SO3? - CORRECT ANSWER 120°
An aqueous mixture contains CuF2 and BaF2 (Ksp = 3.0×10−6). What should be added to the solution in
order to precipitate CuF2?A. NaFB. H2OC. Ba(NO3)2D. Cu(NO3)2
D. Cu(NO3)2 - CORRECT ANSWER D. Cu(NO3)2
In order to precipitate CuF2 from a solution mixture of CuF2 and BaF2, Cu2+ ions need to be introduced
into the solution. The increase in Cu2+ concentration disturbs the product side of the solubility
equilibrium and causes it to shift toward the reactants. Therefore, adding Cu(NO3)2 as a source of Cu2+
ions will selectively cause the CuF2 in the mixture to precipitate.
According to the following reaction, how many grams of hydrogen gas is formed when 15g of aluminum
reacts with excess acid? - CORRECT ANSWER (15)(3) / (27)
STEP 1: To determine the answer to this question, we need to first find out the limiting reagent. Since
HCl is in excess, Al will be the limiting reagent. Remember, the limiting reagent is what determines the
extent to which the reaction would proceed.
STEP 2: Now we can calculate the number of moles of Al below.
moles of Al = (mass) / (molar mass)
moles of Al = (15g) / (27g/mol)
STEP 3: Next, we can determine how much moles of hydrogen is present relative to the number of
aluminum moles. Keep in mind, there are 3 moles of hydrogen for every 2 moles of aluminum.
moles of hydrogen = moles of Al x (mole ratio of H to Al)
moles of hydrogen = (15/27) x (3 mol H2/2 mol Al) = (15)(3) / (27)(2)
STEP 4: Lastly, we can calculate the grams of hydrogen below.
, grams of hydrogen = moles of hydrogen x molar mass
grams of hydrogen = [(15)(3) / (27)(2)] x 2 = (15)(3) / (27)
Which of the following elements exists as a diatomic gas in its standard state and contains a double
covalent bond? - CORRECT ANSWER Oxygen
Which of the following pairs are typically found in alkaline buffer solutions? - CORRECT ANSWER Weak
base and conjugate acid
Which of the following is TRUE for a reaction occurring at 25°C that has a positive ΔH value? - CORRECT
ANSWER The reaction will be spontaneous if delta H is LESS THAN delta S
A 200g sample of mercury at 25°C was heated to 75°C with the addition of 3kJ of energy. Calculate the
specific heat of mercury in J/g°C. - CORRECT ANSWER (3000) / (200)(50)
STEP 1: To determine the answer to this question, we need to utilize the following equation:
q = mcΔT
q = heat gained (positive value) or lost (negative value)c = specific heat capacity of an object at a given
state (changes depending on whether it's liquid, solid or vapor phase)ΔT = final temperature - initial
temperature
Note: When using this equation, it is important to make sure that the units are identical in order for
them to cancel out. Also, be sure to convert 3KJ to 3000 Joules OR change the units for specific heat to
KJ/g°C.
STEP 2: To solve, simply plug in the values into the equation in order to derive the answer:
q = mcΔT → c = q/mΔT
c = (3000J) / (200g * (75°C - 25°C))
c = (3000) / (200*50)
Which one of the following properties applies to alkaline earth metals? - CORRECT ANSWER Form 2+
cations
Vaporization is which of the following types of processes? - CORRECT ANSWER Endothermic
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