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ACS General Chemistry Exam 2024/2025 Questions With Completed & Verified Solutions.
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ACS General Chemistry Exam 2024/2025 Questions With Completed & Verified Solutions.
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ACS General ChemistryWhat is the equation to find the Freezing point Depression? What is i and its two rules?
and what is the Kf(Constant) for water? - ANS delta T (freezing point)=m(molality) * Kf * i
water Kf=1.86*C/molal
Van't Hoff Factor (i) :how much particle dissolves
-ionic compounds separate in solution --depending how many ions they have
-molecular compounds don't separate at all
Which metals in the Periodic table react vigorously with water @25*C and out of that group,
which elements are the most reactive? - ANS Group 1 Alkali Metals
Going down the group, the element is more reactive
Which elements make colored aqueous solutions - ANS Transition Metals except Zn and Pb
Diamond is an example of what kind of solid? - ANS Network Covalent
What is the equation for the First Law of thermodynamics? - ANS Delta E= q + w
For a cubic unit cell, by what fraction do you multiply the number of atoms in the corners and the
atoms in the middle of the vertical corners, - ANS In a cube, there are 8 corners so you would
multiply
8 * (1/8)= 1
In each border of the cube there is an atom in the middle,
there are 12 borders
12 * (1/4) = 3
How many atoms per unit cell do each have:
1. Hexagonal closed packed
2. Body centered cubic cell
3. Face centered cubic cell - ANS a. 6
b. 4
c. 2
#2 A 10.00 g sample of a soluble barium salt is treated with an excess of sodium sulfate to
precipitate 11.21 g BaSO4 (M = 233.4). Which barium salt is it?
(A) BaCl2 (M = 208.2)
(B) Ba(O2CH)2 (M = 227.3)
(C) Ba(NO3)2 (M = 261.3)
(D) BaBr2 (M = 297.1) - ANS Steps:
1.) Write equation with "X" variable
2.) use precipitate mass to find moles
, 3.) Divide given salt mass(grams) over moles of the precipitate.
Answer: BaCl2
#6 Which aqueous solution exhibits the largest freezing point depression?
(A) 1.0 m KBr (C) 0.5 m MgCl2
(B) 0.75 m C6H12O6 (D) 0.25 m Ga2(SO4)3 - ANS Answer: KBr
When alpha particles were shot at a metal foil target to probe the structure of the atom most of
the particles passed through without any deflection in path. Some particles were deflected at
larger angles. This indicated to Rutherford that.......
(a) the metal foil was continuos matter
(b) the mass of the metal atoms was spread out evenly
(c) the atoms of the metal were mostly empty space
(d) the alpha particles had great penetrating power - ANS Answer: The atoms of metal were
mostly empty space.
(the large scattering angles of the alpha particles were only consistent in a small dense center.
The rest of the atom had to be mostly empty space.
#8 Which metal reacts most vigorously with water at 25 °C? and why?
(A) Na (B) Mg (C) K (D) Ca - ANS Answer: K
The further left an element is on the periodic table the more reactive it is with water.
*Group 1 alkali metals most reactive--and within that group, the lower the metal is in the column,
the more reactive it is*
#9 Each of the following forms a colored aqueous solution EXCEPT
(A) Cr(NO3)3 (C) Cu(NO3)2
(B) Co(NO3)2 (D) Zn(NO3)2 - ANS Answer: Zn(NO3)2
*Transition metals make colored aqueous solutions except Pb 2+ and Zn 2+
#12 Which compound has the lowest normal boiling point?
Also, what are the first two things one should look at when doing this question?
(A) HF (B) HCl (C) HBr (D) HI - ANS Answer: HCl
First: look for the type of intermolecular forces (the strongest force is Hydrogen bonding which is
a H bonded to N,O,F)
Second: If there are same forces then you look at the molar mass---b/c the higher the molar
mass, the higher the boiling point
#13 Which of the following would lead to an increase in the vapor pressure of a liquid?
What does volatile mean?
I. Increasing the temperature
II.adding a nonvolatile solute - ANS Answer: only I
You can increase the vapor pressure by increasing temperature
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