Sig Figs
How many significant figures are in the number 45.2?
What rule explains your answer?
3 significant figures
Rule: All nonzero digits are significant.
Which lab tool is used to measure the volume of a liquid most accurately?
Graduated cylinder
This could have been the amount of water or the amount of fertilizer in your radish lab.
Independent variable
__H2 + __ O2 --> H2O
2, 1, 2
What rule helps explain why the noble gases are stable/unreactive?
How many significant figures are in the number 0.00780?
What rule explains your answer?
3 significant figures
Rule: Leading zeros are not significant, but trailing zeros to the right of a decimal are significant.
What tool should you use to safely pick up a hot beaker?
Tongs or mits
If scientists want to know how bad a car is for the environment, they might measure the amount of CO2 different engines produce. In an experiment, this amount of CO2 would be the _____?
Dependent variable
__Al + ___ O2 --> ___Al2O3
4, 3, 2
Draw NH3. Name the type of bond(s) it has.
N with three covalent bonds (one to each H).
Round 18.467 to 3 significant figures.
What rule explains your answer?
18.5
Rule: When rounding significant figures, look at the digit after the last sig fig. If it is 5 or greater, round up.
A scientist needs to heat a liquid to exactly 75°C while monitoring the temperature. Besides a beaker, which TWO lab tools are most important?
A hot plate (or Bunsen burner) and a thermometer.
Scientists often try to find two sites in the wild that have lots of things in common to use as "outdoor laboratories" (e.g. two ponds next to each other). These make for great experiments because of the amount of _____ that scientists can count on.
constants
__Na + ___Cl2 --> __NaCl
And, what rule are we using to determine these numbers??
2,1,2
The Law of Conservation of Mass
In order for these elements to bond, there must be at least how many of each?
Na, S
2 Na, 1 S
A student measures a pencil to be 12.040 cm long.
What rule explains your answer?
5 significant figures
Rule: Zeros between nonzero digits are significant, and trailing zeros after a decimal are also significant.
It would be smartest to mix baking soda and vinegar in this container to limit the mess you'd make.
Erlenmeyer flask
The reddish apple having 95 calories, weighed as much as a standard deck of cards; this was more than the green apple that stood at four inches tall, despite the molding.
How many quantitative and qualitative data points (combined) were in the sentence above.
- list each from each category
7 data points
Quantitative (2): 95 calories, 4 inches tall
Qualitative (5): color = red, weight = deck of cards, weight = green lighter than red apple, color = green, state = molding
___Fe + ___ O2 --> Fe2O3
4,3,2
Name these:
N2O5
SF6
dinitrogen pentoxide
sulfur hexafluoride
Calculate the answer using the correct number of significant figures:
(4.56×2.1)+0.003
What rule explains your answer?
9.6
Rule: In multiplication/division, the answer must have the same number of significant figures as the value with the fewest sig figs. Since 2.1 has 2 sig figs, the final answer must have 2 sig figs.
Pipette.
Place the following steps in the proper order.
- analyze data, observe, repeat, hypothesize, test, question, gather results, update hypothesis or test
observe, question, hypothesize, test, gather results, analyze data, update hypothesis or test, repeat
___C3H8 + ___O2 ---> CO2 + H2O
1,5,3,4
What is unique about this atom. Provide the key term(s).
Carbon: 6 protons, 5 electrons, 8 neutrons
It is an ion (1 fewer e-) and an isotope (2 extra neutrons)