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17 terms

Chemistry #2

chemistry #2
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significant figures
the digits in the measurement that are known with certainty plus one digit that is uncertain
#Sig. fig. = all certain numbers + one uncertain number
leading zeros
those at the beginning of a number are NEVER significant.
ex. 0.00035 has 2 sign. #
confined zeros
those between nonzero digits are ALWAYS significant
ex. 3.0689 has 5 significant figures
Trailing zeros
those at the end of the a number, are significant only if a decimal point is present in the number.
35.00 has four sig.fig.
0.05060 has four sig.fig.
86,000. has 5 sig.fig.
Trailing zeros (no decimal point)
are not significant if the number lacks a decimal point.
6,000,000 has one sig. fig.
70050 has four sig. fig.
Significant figure: multiplication and division
- is the same as the number of significant figures in the measurement that contains the fewest significant figures.
- In multiplication and division significant figures are counted.
Significant figure:
- the answer has no more digits to the right of the decimal point than are found in the measurement with the fewest digits to the right of the decimal point.
- In addition and subtraction, decimal places are counted.
scientific notation
- With scientific notation...only significant figures appear in the coefficient.
Ex. 86 ---> 2 Sig. Figs. ----> 8.6 x 10¹
Ex. 86.0 --->3 sig. figs. ---->8.60 x10¹
density
the ratio of the mass of an object to the volume occupied by that object

density = mass/volume
Kevlin & Celsius
K = C =273
C = K - 273
Farrenheit & Celsius
F = 9/5(C) + 32
C = 5/9(F -32)
calorie
the amount of heat energy needed to raise the temperature of 1 gram of water by 1 degree celsius
kilocalorie
1 kilocalorie = 1000 calories
joules
1 calorie = 4.184 joules
specific heat
the quantity of heat energy, in calories, necessary to raise the temperature of 1 gram of a substance by 1 degree celsius.
heat absorbed
= specific heat X mass X temperature change
volume
length X width X height