Lab Calculations
The actual yield in an experiment is 3.0 grams. If the theoretical yield was 4.0 grams, what is the percent yield?
75%
Write the p+, no, and e– of the following ion, 58Ni2+
p+= 28 no=30 e–=26
What is the molarity of 1.1 mol of NaC2H3O2 dissolved in 280 mL solution?
3.9 M
What is Avogadro’s number (with units)?
6.022×1023 things per mole
If you start with 6 grams of hydrogen and 6 grams of nitrogen, which reactant will limit the amount of product in the following reaction?
3 H2 + N2 → 2 NH3
Nitrogen will limit.
6 g H2 ×(1 mol H2÷2 g H2)×(2 mol NH3÷3 mol H2) = 2 mol NH3
6 g N2 ×(1 mol N2÷28 g N2)×(2 mol NH3÷1 mol N2) = 0.4 mol NH3
What 2 things effect the atomic radius?
Atomic pull (nuclear force) and number of energy levels
What is the electron configuration for bromine?
1s2 2s2 2p6 3s2 3p6 4s2 3d10 4p5
[Ar] 4s2 3d10 4p5
How many moles of iron are in 2 mole of Fe3(PO3)2?
There are 6 moles of Fe in that compound.
Dr. Nefario predicted a theoretical yield of 0.50 g. If he had a 90% yield, what mass of product actually formed?
0.45 g
Draw the Lewis structure for NO3–
N is in the middle, there are two single bonds and one double bond with three resonance structures.
What are the solute(s) and solvent in dirty dish water?
Solute = dish grime and soap
Solvent = water
How many moles are in 4.22×1025 Calcium atoms?
70.1 moles
What is the theoretical yield if 2 g of H2 react with excess O2 to form water?
___H2 + ___O2 → ___H2O
18 g H2O
2 g H2 ×(1 mol H2÷2 g H2)×(2 mol H2O÷2 mol H2)×(18 g/mol H2O)
Why are ionization energy and atomic radius opposite trends of each other?
The smaller the atom, the harder it is to remove electrons.
What kind of bond is formed in SH2?
Covalent bond
Bonus: draw the Lewis Dot Structure (hint there are two lone pairs of electrons)
How many moles are in 72 grams of water?
4.0 mol
What is the percent yield if 4.0 g of magnesium react with an excess of oxygen and 5.5 g of magnesium oxide is actually formed? Balance equation.
___Mg + ___O2 → ___MgO
83%
4.0 g Mg = 0.1646 mol Mg → 0.1646 mol MgO = 6.6 g MgO
(5.5 g÷6.6 g)×100% = 83%
What subatomic particle effects the stability of the atomic nucleus?
Neutrons. Different isotopes of an element have different stabilities, which is why some isotopes are more or less radioactive than others.
Define a covalent bond. What do the electrons do in a covalent bond?
Two non-metals share electron pairs. Alternatively, a metalloid and a non-metal share electron pairs.
In the following reaction, if you are given 11 moles of O2 and 12 moles of PbSO3, how many moles of PbSO4 can you make?
__PbSO3 (s) + __O2 (g) → __PbSO4 (s)
12 mol of PbSO4