Chem 55 Exam 2 Solutions

CHEM 55 Fall 2007 Exam 1 Copy # 1
Name: Au,Hai Nguyen
Values of Student's t
% confidence interval
°freedom 50 80 95 99
1 1.00 3.08 12.71 63.66
2 0.82 1.89 4.30 9.92
3 0.76 1.64 3.18 5.84
4 0.74 1.53 2.78 4.60
5 0.73 1.48 2.57 4.03
6 0.72 1.44 2.45 3.71
7 0.71 1.41 2.36 3.50
8 0.71 1.40 2.31 3.36
9 0.70 1.38 2.26 3.25
10 0.70 1.37 2.23 3.17
20 0.69 1.33 2.09 2.85
50 0.68 1.30 2.01 2.68
100 0.68 1.29 1.98 2.63
∞ 0.67 1.28 1.96 2.58
Values of Q for rejection of data:
Q
90% confidence
Number of
Observations
0.76 4
0.64 5
0.56 6
0.51 7
0.47 8
0.44 9
0.41 10
Average, Sample standard deviation
and confidence interval formulae:
x =
n
∑
i=
1
n
n
x
∑
( xi
− x)
i=
1
s =
n −1
CI = x ±
ts
n
( x − μ)
t =
s
i
n
2
Error propagation formulae:
for : y = x1
+ x2
for : y = x1⋅
x2
for : y = log( x)
for : y = 10
for : y = ln( x)
for : y = e
for : y = x
x
a
x
e
e
y
y
% e
y
e
y
% e
y
=
=
ex
ey
=
x
= y ⋅e
x
e
2
x1
= a ⋅%
e
% e
x
+ e
2
x1
ex
ey
= 0.434
x
= 2.303⋅
y ⋅e
x
2
x2
+ % e
2
x2