Quiz
Note: It is recommended that you save your response as you complete each question.
Question 1 (2 points)
In a gravimetric determination of lead content in brass, there is a constant loss by solubility of
0.50 mg of lead.
A sample contains 6.98% by ma
Question 1 (2 points)
The solubility of strontium carbonate is 0.0011 g/100 mL at 20C. Calculate the Ksp value for this
compound.
Question 1 options:
1.5 104
5.6 109
1.5 103
7.5 105
7.5 106
http:/answers.yahoo.com/question/index?qid=20090725120149AAqnwhr
Review-MT-2+ answers
1. Calculate the pH of a 0.030 M NH4Cl solution. (Ka = 5.6 x 10-10) (Ans: 5.4)
2. Calculate the pH of a 0.14 M solution of NaF. (Ka = 7.2 x 10-4) (Ans: 8.1)
3. Which of the following has the highest pH?
a) 0.10 M NaCl
b) 0.10 M HCl
(A
Review-MT-1 + answers
1.Which of the following is the best way to dispense 100.0 mL of a reagent:
(a) use a 50.00mL 0.03mL pipet twice;
100.00mL 0.04mL-using the 50.00mL pipet twice
(b) use a 25.00mL 0.03mL pipet four times; or
(c) use a 10.00mL 0.02mL pi
Formula Sheet-MT-1
W1 = W2 + W2 (dair/dobj dair/dwts)
Xi
X=
N
CV =
dair = 0.0012 g/cm3
di =( X i - X ) ,
s
x 100
X
CL ( ) = X
Relative error =
t.s
| ( Xi - X ) |
d=
N
(X -)
x
t =
w
t =
z.
N
Qexp =
w
( X i - X )2
(N - 1)
(x ) N
s
(X i - X )2
=
s pooled
Eng Tech 1AC3
Exercise 1
Student ID#:_
Topic: Gravimetric Analysis Sample Calculations
Q1. A 0.4016g sample of a commercial phosphate detergent was ignited at a red heat
to destroy the organic matter. The residue was taken up in hot HCl, which converted
t
Errors in Chemical Analysis
Examples:
1. Three measurements were made of the percent by
mass of chloride in an impure salt sample: 60.53%,
60.37%, 60.29%. Calculate the mean, the mean
deviation and the sample standard deviation.
2 An
2.
A analysis
l i wa
Question 1 (2 points)
The solubility of strontium carbonate is 0.0011 g/100 mL at 20C. Calculate the Ksp value for this
compound.
Question 1 options:
1.5 104
5.6 109
1.5 103
7.5 105
7.5 106
Question 2 (1 point)
The solubility product for barium sulfate is
Experiment 2: Report Forms
Name
Partner
Date
Lab section
Table 1: Sample Weighing
Cast Iron Sample Number
Trial 1
Trial 2
Weight of bottle + lid + sample
g
g
Weight of empty bottle + lid
g
g
Weight of sample
g
g
Crucible 1- Trial1
Crucible 2- Trial
2
Weig
Experiment 3: Report Forms
Name
Date
Lab section
Step 1: Preparation of Sample solution
IDENTITY OF SAMPLE
=
Wt. of bottle + sample
=
g
Wt. of bottle after transfer
=
g
Wt. of sample used
=
g
Dissolved in distilled water and made to
_
mL.
Step 2: Preparat
Experiment 1: Report Forms
Name
Date
1.
Lab section
Operation of the Analytical Balance (each number below corresponds to its
instruction in the Lab Manual)
2.
g
3.
g
4.
g
a. Sum of (2 + 3)
g
5.
g
6.
g
b. Difference of (5 - 2)
g
c. Difference of (6 - 5)
g
Analysis of the sample
Samples rarely "bench ready" for analysis
Pre-treatments of various kinds May include removal of INTERFERENCES
Substances that "add on" to the result, or decrease the apparent analyte level, or otherwise interfere with the chemis
Course policies
Attendance
It is the students responsibility to make up course work for missed lectures and missed laboratory sessions
Due to absence with permission or suitable explanation, as indicated in policy of Labs below in policy of Labs below
Errors in Chemical Analysis
Examples:
1. Three measurements were made of the percent by mass of chloride in an impure salt sample: 60.53%, 60.37%, 60.29%. Calculate the mean, the mean deviation and the sample standard deviation. 2. An analysis was carrie
Significant digits
All non-zero digits are significant Zeros are significant if:
Between significant figures
E.g. 504
Right of decimal and right of significant figures of decimal and of significant figures
E.g. 14.50
If it does not meet both, its no
Module 4
Gravimetric Analysis
4.1 Explanation of gravimetric analysis and calculations involving unit-dimensional analysis and percentage composition by mass.
4.2 Definition and utility of the gravimetric factor for routine calculations 4.3 Solubility,
Module 3 Data Treatment
Statistical Analysis
Gaussian distribution; sample and population; sample mean and population mean; sample standard deviation and the population standard deviation; relative standard deviation (RSD) and coefficient of variation (
Standard deviation
Improving the value of standard deviation
Sometimes you may have a small set of results, but the same type of analysis has been done many times in the past on other samples You can use standard deviations calculated from can use stand
Statistical comparison tests
Comparisons between different sets of data are required in chemical analysis in the following instances:
Comparing a result with a standard Comparing the results of the same analysis by the results of the same analysis by tw