AS.030.105 Study Guide - Midterm Guide: Burette
Chem Lab I Exam 1 Note Card Info
Sig Figs:
• Percent Deviation: # of sig figs in % deviation is ALWAYS the # of sig figs in subtraction in
the numerator
o Formula:
!""
#
$%&'$()&*+,-+&.%$(
&*+,-+&.%$( /
• Percent Yield:
o Formula: 100(
$%&'$(01.+(2
&*+,-+&.%$(01.+(23
• Standard Deviation: leading digit of 1 = 2 sf, otherwise just 1 sf
o * look at “MAXIMUM” stuff on sig figs sheet (pg 1), these are limited further by
the decimal position of the least significant digit of std. dev.
o Formula:
0
4
0
5
678)7
9
3:
8
;<)=
(LINEST function in Excel used to determine std. dev. of
slope and intercept)
• Uncertainties in measurement:
o Reading digital measuring devices: the last digit shown is the least sig digit
o Reading graduated measuring devices: estimate the value to one decimal place
more than the gradation (0.1 mL increments on glass burette = recorded to .01
mL)
• Sig Fig Algebra Rules:
o All nonzero digits are significant (1.234 = 4 sf)
o Zeroes between nonzero digits are significant (1.02 = 3 sf)
o (0.012 = 2 sf)
o (0.120 = 3 sf)
o (100 = 1 sf)
o (1.0 x 102 = 2 sf)
o (100. or 1.00 x 102 = 3 sf)
o (100.0 or 1.000 x 102 = 4 sf)
o Addition/Subtraction: round off result to the leftmost decimal place (40.123 +
20.34 = 60.46), (4.25E5 + 3.23E3 = 4.25E5 + 0.323E5 = 4.28E5)
o Multiplication/Division: round off the result to the smallest # of sig figs (1.23 x
2.0 = 2.5, not 2.46)
o Exact # (60 seconds in a minute, 24 hours in a day, etc) never limit # of sig fig
(325 seconds/60 seconds = 5.42 minutes)
o Logarithms: log(12.8) = 1.107 (mantissa is .107 = 3 digits = 3 sf = 12.8), log(10.5) =
1.021 (mantissa is .021 = 3 digits = 3 sf = 10.5) *it is # of digits in mantissa, not sf!
o Exponents: 101.23 = 17 = 1.7E1 (2 digits = mantissa (.23)), 101.03 = 11 = 1.1E1 (2
digits = mantissa (.03))
o (2.44 x 2.0) + 2.96 = 4.88 + 2.96 = 7.84 = 7.8
o avg of 122 and 123 = 123
>
0.5
Exp 2:
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Exp 3
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