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chemistry #2

### 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

### 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

### calorie

the amount of heat energy needed to raise the temperature of 1 gram of water by 1 degree celsius

### specific heat

the quantity of heat energy, in calories, necessary to raise the temperature of 1 gram of a substance by 1 degree celsius.