Practice exam tonight
A103, 7-9 pm
CHEM 180 for next semester
Experimental recitation for CHEM 113
Optional, not connected to lecture
Only homework would be model-type assignments
In-class, worksheet based class
Refined model assignment
Due Wed, 11 / 17
2 Mg (s) + O (g) → 2 MgO (s)
How much MgO is formed if 30 g of Mg reacts completely?
1.2 mol MgO x (2431 + 16) g / 1 mol MgO = 50 g MgO
At STP, how many liters of O a2e needed to completely react those 30. g of Mg?
30 g Mg x 1 mol Mg / 24.31 g x 1 mol O / 2 2ol Mg x 22.4 L / 1 mol O 2
14 L of O2
The study of the quantitative aspects of chemical formulas and reactions
The coefficients of a formula give the stoichiometric ratios of compounds in a reaction Solution example
Given the following equation:
NaOH (s) + HCl (aq) → NaCl (aq) + H O (l2
How many liters of a 10.0 M solution of HCl would react with 5.00 g of solid NaOH?
5 g NaOH → L HCl sln
5 g NaOH x (1 mol NaOH / 40 g NaOH) x (1 mol HCl / 1 mol NaOH) x (1 L HCl / 10 moles
HCl) = 0.0125 L
A group of students determines the ion crowdness index of a 15.0 L solution to be 6.00 moles of
ions per liter of solution. If 25.0 liters of water are added to the solution, what is the ion
crowdness index of the new solution?
A. 0.15 moles of ions / liter of solution
B. 2.25 moles of ions / liter of solution
C. 3.60 moles of ions / liter of solution
D. 6.00 mole