Ch. 2: Measurements & Calculations. An Introduction to Scientific Investigations. What is Chemistry?. Chemistry - the study of substances and the changes they can undergo. EX: a match burning, how bleach removes stains, why bread dough rises, etc. A) The Central Science
An Introduction to Scientific Investigations
Area- length X width = m X m= m2
Volume- the amount of space that an object occupies.
Length X width X height = m X m X m= m3
The liter (L)- the common unit for volume. 1mL= 1cm3
Celsius (C)- common unit for temperature
1K = (273 + C)
Hint: look at the meniscus.
Measurements can be checked for precision and accuracy to determine their reliability.
Hint: Change the number to scientific notation. It is easier to see.
When rounding off numbers to a certain number of significant figures, do so to the nearest value. Round like normal.
Of course, if we round to 2 significant figures:
2.452 x 102 is closer to 2.5 x 102 than 2.4 x 102.
Some of the basics of exponential mathematics are given below.
22 = 2 x 2 = 4 105 = 10 x 10 x 10 x 10 x 10 = 100,000
The following rule can be used to convert numbers into scientific notation: The exponent in scientific notation is equal to the number of times the decimal point must be moved to produce a number between 1 and 10.
Ex: In 1990 the population of Chicago was 6,070,000. To convert this number to scientific notation we move the decimal point to the left six times.
10,300,000,000,000,000,000,000 = 1.03 x 1022
You can change fractions to percent by dividing the top number by the bottom number and multiplying by 100 =%
PRESENTING SCIENTIFIC DATA: