Sig Figs and Measurements
How many significant figures are in 1.00 ?
There are three significant figures!
Which is correct:
Liquids have form, solids change to their environment, gas has no form
Liquids change to their environment, solids have no form, gas has form
Liquids change to their environment, solids have form, gas has no form
Liquids change to their environment, solids have form, gas has no form
How many protons and electrons are in a neutrally charged oxygen atom?
8 protons, 8 electrons
Write the dissociation of HCl into water.
HCl + H2O --> H3O+ + Cl-
H3O+ is equivalent to H+
How many moles of water are in ~36.03 grams of water?
Two moles (molar mass of water is 18.01528~ g/mol)
What is the way to write 0.00000015 in scientific notation ?
0.00000015 = 1.5 x 10^-7
What kind of mixture is an oil and vinegar salad dressing?
Heterogenous mixture
What are the differences between atomic number and mass number and atomic mass?
Atomic number is the # of protons in the nucleus, while mass number is the # of protons and neutrons, and mass number is the average of the masses of all isotopes for the element.
Name this compound: HBr
Hydrobromic acid
If I have a sample that has 2.34 moles of iron present, how many molecules of iron do I have?
2.34 x 6.022 x 10^23 molecules = 1.409 x 10^24 molecules of Fe.
What is the answer to the following math problem (consider how many significant figures will be in your answer)?
(3.05 x 2.0) / (6.02 x 3.0)
0.34 with only two significant figures
What kind of change is the burning of wood?
Chemical change.
Which of these ions can be correct?
H- , Cl- , H+ , Cl+ , O 2- , NO3 2- , PO4 3- , ClO2 4-
H- is possible, as are Cl- , H+ , O 2-, PO4 3-
Name this compound: N2O
Dinitrogen Monoxide (aka nitrous oxide)
If I have a sample with 4.032 grams of Hydrogen, but 12.011 g of Carbon, what percent of the mass is hydrogen?
(4.032)/(4.032+12.011) x 100% = 25.13%
What is the molarity of a solution with 1.45 moles of substance X in 0.555 L?
2.61 M solution of substance X
How much energy is there if I combust 3.5 moles of C3H8 with excess oxygen? (and is it endothermic or exothermic)
delta H (rxn) = 103.9 kJ/mol
363.65 kJ produced in an exothermic reaction
14.003 amu at 99.63% abundance
15.000 amu at 0.37% abundance
(14.003)(0.9963) + (15.000)(0.0037) = 14.006 amu = Nitrogen!
Name the following ions: Cl- , PO4 3- , ClO3 -
Chloride, Phosphate, Chlorate
From the last problem, a sample with 4.032 grams of Hydrogen, but 12.011 g of Carbon, what is the chemical formula? (hint: convert to moles)
CH4
4.032 g of H = 4 mol of H
12.011 g of C = 1 mol of C
Find the density, in g/mL, of a 10 mL sample that weighs 0.38 kg.
38 g/mL
Think of examples of an endothermic reaction and an exothermic reaction.
Free response, check answers together.
What is this element/isotope?
5224X
Chromium-24
Name the following compounds: NH4Cl , AlPO4, FeSO4
Ammonium Chloride, Aluminum Phosphate, Iron (II) Sulfate
C6H8, N2O4, C2H6O2
C3H4, NO2, CH3O