Sig Figs & Scientific Notation
3 sig figs
145,000What are the four gas variables?
Pressure (P), Volume (V), Amount of gas (n), Temperature (T)
A drink mix packet is added to a bottle of water. What is the solvent in this solution?
The water
(what dissolves the solute)
What is the molar mass of Mg(OH)2 rounded to one decimal place?
58.3 g/mol
What is used to balance chemical equations?
Coefficients
What is 0.000304 in scientific notation?
3.04 x 10-4
If you decrease the volume of a gas, what happens to the pressure?
It increases
(indirect relationship)
What is the term for when moles of solute are kept constant but the volume of the solution is increased?
Dilution
___ Cs + ___ N2 --> ___ Cs3N
What is the coefficient of Cs when the equation is balanced?
6
(6 Cs + N2 --> 2 Cs3N)
What is the significant figure rule for addition and subtraction?
Answer will be rounded to least number of decimal places
How many significant figures are in 0.003400?
4 sig figs
0.003400
A 15 L gas at 1.5 atm is compressed to 8.5 L. What is the new pressure?
P2 = 2.8 atm
P1*V1 = P2*V2
A solution is made with 38 moles of solute and has a total volume of 76 liters. What is the molarity of the solution?
0.5 M
M = n / V
How many moles are in 100. g of H2O? (round to three sig figs)
5.56 mol H2O
(moles = grams / molar mass)
What are the units used for the ideal gas constant?
404 x 120 = ?
48,000
48,480 --> 48,000 (2 sig figs)
A 5.0 L gas at 350 K is cooled to 273 K. What is its new volume?
V2 = 3.9 L
V1 / T1 = V2 / T2
A 5.0 L solution has a concentration of 5.0 M. How many moles of solute were dissolved?
25 mol
n = M x V
2 Al(OH)3 + 3 H2CO3 --> Al2(CO3)3 + 6 H2O
How many moles of water will be produced if you react 7.5 moles of Al(OH)3 with excess H2CO3?
22.5 mol H2O
(6 mol H2O / 2 mol Al(OH)3)
What is the equation used for dilution calculations?
M1*V1 = M2*V2
17.89492 - 12.491 = ?
5.404
5.40392 --> 5.404 (3 decimal places)
An ideal gas has a pressure of 2.0 atm, volume of 4.2 L, and temperature of 22 oC. How much gas is there?
n = 0.35 mol
PV = nRT
How much water do you need to add to 3 L of a 22 M solution in order to dilute the concentration to 6 M?
8 L of water added
M1*V1 = M2*V2 --> V2 - V1 = 8 L
2 Al(OH)3 + 3 H2CO3 --> Al2(CO3)3 + 6 H2O
How many grams of H2O will be formed if you react 124 grams of H2CO3 with excess Al(OH)3?
18 g H2O
124 g H2CO3 * (1 mol H2CO3 / 62 g H2CO3) * (6 mol H2O / 3 mol H2CO3) * (18 g H2O / 1 mol H2O)
2 N2 + 5 O2 --> 2 N2O5
How many moles of N2O5 will be produced if 3.01*1023 molecules of O2 react with excess N2?
0.2 mol N2O5
3.01*1023 molec O2 * (1 mol O2 / 6.02*1023 molec O2) * (2 mol N2O5 / 5 mol O2)