Molar Concepts
Determine the mass in grams of 7.75 × 10²¹ atoms of carbon. (The mass of one mole of carbon is 12.01 g.)
0.155 g
If 4.9 kg of CO₂ are produced during a combustion reaction, how many molecules of CO₂ would be produced?
6.7 × 10²⁵ molecules
143
How many significant figures does the number 48.050 have?
5
What is the coefficient in front of the NO when the equation below is balanced?
NH₃(g) + O₂ (g) → NO(g) + H₂O (g)
4
4NH3(g)+5O2(g) →4NO(g)+6H2O(g)
Determine the number of atoms in 71.0 grams of nickel, Ni. (The mass of one mole of nickel is 58.69 g.)
7.29 × 10²³ atoms
What is the mass in grams of 42.30 moles of LiCl?
1793 g
What is the difference between a chemical change and a physical change?
Chemical: when one chemical substance is transformed into one or more different substances (EX: Iron oxidizing into rust)
Physical: usually reversible change in the physical properties of a substance, as size or shape (ripping paper in half)
How many significant figures does the number 1.006 × 10⁷ have?
4
What is the coefficient in front of the O₂ when the equation below is balanced
C₂H₄(g) + O₂ (g) → CO₂(g) + H₂O (g)
3
C2H4(g)+3O2(g) →2CO2(g)+2H2O(g)
What quantity in moles of potassium atoms do you have if you have 3.50 × 10²² atoms of potassium? (The mass of one mole of potassium is 39.10 g.)
0.0581 mol
Determine the number of atoms of O in 62.3 moles of Na₂Cr₂O₇.
2.63 × 10²⁶ atoms
B) Beryllium
The alkaline earth metals are found in Group 2 and include Be, Mg, Ca, Sr, Ba, and Ra.
Calculate the answer and report the correct number of significant figures.
1.030 g ÷ 2.87 mL
0.359 g/mL
Balance the following chemical reaction:
Al₂(SO₄)₃ (aq) + K₃PO₄ (aq) → AlPO₄ (s) + K₂SO₄ (aq)
Al₂(SO₄)₃ (aq) + 2 K₃PO₄ (aq) → 2 AlPO₄ (s) + 3 K₂SO₄ (aq)
Determine the mass, in grams, of 0.400 moles of Pb (1 mol of Pb has a mass of 207.2 g).
82.9 g
Determine the number of atoms of H in 35.0 grams of C₂H₄O₂.
1.40 × 10²⁴ atoms
What differentiates an ionic compound and a covalent compound?
Ioinic: Metal + Nonmetal (NaCl)
Covalent: Nonmetal + Nonmetal (CO2)
Calculate the answer and report the correct number of significant figures. 3.24 m x 7.0 m
23 m²
4 Si₂H₃(s) + 11 O₂(g) → 8 SiO₂(g) + 6 H₂O(g)
Consider bromine, which occurs as a mixture of two isotopes: bromine-79, with a natural abundance of 50.7% and an exact mass of 78.92 amu, and bromine-81, with a natural abundance of 49.3% and an exact mass of 80.92 amu. What is the average atomic mass of bromine?
79.9 amu
average atomic mass can be calculated by the following weighted average:
(78.92amu×0.507)+(80.92amu×0.493)=79.9amu
If 28.0 g of NaOH is added to 0.550 L of 1.00 M Ni(NO₃)₂, how many grams of Ni(OH)₂ will be formed in the following precipitation reaction? 2 NaOH(aq) + Ni(NO₃)₂(aq) → Ni(OH)₂ (s) + 2 NaNO₃ (aq)
32.4 g
total number of protons and neutrons in the atom
A cup of hot soup is initially at 85.4 °C, then cools by 33 °C over a period of 25 minutes. Choose the value that expresses the new temperature of the soup after 25 minutes using the correct number of significant figures.
52 °C
Balance the following chemical equation (if necessary):
C₅H₁₀O(l) + O₂(g) → H₂O(g) + CO₂(g)
C₅H₁₀O(l) + 7 O₂(g) → 5 H₂O(g) + 5 CO₂(g)