CHEM 115 CORE EXAM SET 2026/2027 QUESTIONS AND
SOLUTIONS RATED A+
✔✔How many grams of Br are found in 195 g or CaBr2 - ✔✔Br= 79.904
Br2= 159.808
Ca= 40.078
CaBr2= 40.078 + 2(79.904) = 199.886
195/199.886 = .9755
.9755 • 159.808 = 155.902
✔✔when dealing with ions, elements always lose or gain _____ - ✔✔ELECTRONS
✔✔molecular geometry: seesaw degrees - ✔✔90° and 120
✔✔how many moles of CaCl2 are in 7.74 • 10^23 formula units - ✔✔7.74 • 10^24 /
(6.022 • 10 ^23)
= 12.853
✔✔molecular geometry: T-shaped - ✔✔90°
✔✔reaction produces .886 moles of H2O. How many molecules of H2O are produced -
✔✔(6.022 • 10^23) • (.886)
= 5.335 • 10^23
✔✔molecular geometry: octahedral degrees - ✔✔90°
✔✔a zinc ring is composed of 1.87 • 10^23 atoms. Calculate the mass of the ring in
grams - ✔✔(1.87 • 10 ^23) / 6.022 • 10^23
= .31053
Mass of zinc= 65.39
.31053 • 65.39
= 20.305
✔✔molecular geometry: square pyramidal degrees - ✔✔90°
✔✔molecular geometry: square planar degrees - ✔✔90° and 180°
, ✔✔how many moles of argon are in 14 g of argon - ✔✔Ar= 39.48
14/ 39.48
= .35461
✔✔calculate the number of atoms in 6.93 • 10^3 g of Lithium - ✔✔Lithium= 6.94
(6.93 • 10^23) / 6.94 = 998.559
998.559 • (6.02 • 10^23) = 6.0133
✔✔how many electron regions does SF4 have (it has 2 bonded areas and 2 lone
pairs)? so what would its hybridization be? - ✔✔4
sp3 (because 4-1=3)
✔✔What type of bond results from the side-on overlap of orbitals? - ✔✔π (pi) bond
✔✔calculate the molar mass of C2H6 - ✔✔C2= 24.02
H6= 6.48
24.02+ 6.48 = 30.5
✔✔calculate the total number of ions in 4.03 mols of MgCl2 - ✔✔4.03 • (6.02 • 10^23) •
3
= 7.28 • 10^24
✔✔What type of bond results from the end-on overlap of orbitals? - ✔✔σ (sigma) bond
✔✔Endothermic reactions are defined by a _____. - ✔✔positive delta H
✔✔each single bond consists of ____ σ (sigma) bond(s) and ____ π (pi) bond(s) - ✔✔1
σ (sigma) bond
0 π (pi) bond
✔✔Specific heat capacity is the - ✔✔quantity of heat needed to raise the temperature of
one gram of a substance by one degree
✔✔each double bond consists of _____σ (sigma) bond(s) and _______ π bond(s) -
✔✔1 σ (sigma) bond
1 π (pi) bond
SOLUTIONS RATED A+
✔✔How many grams of Br are found in 195 g or CaBr2 - ✔✔Br= 79.904
Br2= 159.808
Ca= 40.078
CaBr2= 40.078 + 2(79.904) = 199.886
195/199.886 = .9755
.9755 • 159.808 = 155.902
✔✔when dealing with ions, elements always lose or gain _____ - ✔✔ELECTRONS
✔✔molecular geometry: seesaw degrees - ✔✔90° and 120
✔✔how many moles of CaCl2 are in 7.74 • 10^23 formula units - ✔✔7.74 • 10^24 /
(6.022 • 10 ^23)
= 12.853
✔✔molecular geometry: T-shaped - ✔✔90°
✔✔reaction produces .886 moles of H2O. How many molecules of H2O are produced -
✔✔(6.022 • 10^23) • (.886)
= 5.335 • 10^23
✔✔molecular geometry: octahedral degrees - ✔✔90°
✔✔a zinc ring is composed of 1.87 • 10^23 atoms. Calculate the mass of the ring in
grams - ✔✔(1.87 • 10 ^23) / 6.022 • 10^23
= .31053
Mass of zinc= 65.39
.31053 • 65.39
= 20.305
✔✔molecular geometry: square pyramidal degrees - ✔✔90°
✔✔molecular geometry: square planar degrees - ✔✔90° and 180°
, ✔✔how many moles of argon are in 14 g of argon - ✔✔Ar= 39.48
14/ 39.48
= .35461
✔✔calculate the number of atoms in 6.93 • 10^3 g of Lithium - ✔✔Lithium= 6.94
(6.93 • 10^23) / 6.94 = 998.559
998.559 • (6.02 • 10^23) = 6.0133
✔✔how many electron regions does SF4 have (it has 2 bonded areas and 2 lone
pairs)? so what would its hybridization be? - ✔✔4
sp3 (because 4-1=3)
✔✔What type of bond results from the side-on overlap of orbitals? - ✔✔π (pi) bond
✔✔calculate the molar mass of C2H6 - ✔✔C2= 24.02
H6= 6.48
24.02+ 6.48 = 30.5
✔✔calculate the total number of ions in 4.03 mols of MgCl2 - ✔✔4.03 • (6.02 • 10^23) •
3
= 7.28 • 10^24
✔✔What type of bond results from the end-on overlap of orbitals? - ✔✔σ (sigma) bond
✔✔Endothermic reactions are defined by a _____. - ✔✔positive delta H
✔✔each single bond consists of ____ σ (sigma) bond(s) and ____ π (pi) bond(s) - ✔✔1
σ (sigma) bond
0 π (pi) bond
✔✔Specific heat capacity is the - ✔✔quantity of heat needed to raise the temperature of
one gram of a substance by one degree
✔✔each double bond consists of _____σ (sigma) bond(s) and _______ π bond(s) -
✔✔1 σ (sigma) bond
1 π (pi) bond
