Posted: June 29th, 2022

Chem Exp 11

Math Assignment

Name Matthew Ramirez CHM100 Section 029LS

1. Solve the following: a) 256 × 0.05 =12.8
b) 2.5 × 100 =250

c) 0.035
d) 0.2243
e) 6794.118
2. Express the following exponentially: a) 10,000 = 1.0×104
b) 150 = 1.0 x 102
c) 0.0015 = 1.0 x 10-3
d) 0.023 = 1.0 x 10-2

3. Express the following as whole numbers:

a) = 100
c) = 1000
b) = 0.0016
d) = 0.1
4. If
a) Write an equation for c in terms of a and b
C = b/a

b) Write an equation for b in terms of a and c
b=ac

5. Given that
a) Find
oF = 1.8*20+32
oF = 68

b) Find
(65oF-32)/1.8= oC
oC=18.33

6. Given the following data, fine the average

35.3 35.6 34.9 35.0

Ans = 35.2

7. 2.5 centimeters = 1.00 inches

a) How many centimeters are there in 5.0 inches?
5 x 2.5
= 12.5 c
b. How many inches are there in 21.0 centimeters?

21/2.5 = 8.4 inches
8. The density is defined as the mass of a substance divided by its volume. Determine the density of
9.0 mL of a liquid with a mass of 13.4 grams.

Density = Mass/Volume,
Thus, D=13.4g/9ml
=1.48889 g/ml

9. The density of mercury is 13.5 g/mL. Determine the number of grams found in 30.0 mL of mercury?

Mass= volume*density,
Mass=13.5g/ml*30.0mL
=405g

10. A sample weighing 30.0 grams contains 1.5 grams of salt. Determine the percent salt found in the sample.

percent salt = mass of the salt*100/mass of the solution,
thus (1.5*100)/30
=5%

11. A sample contains 25% water and weighs 201 grams. Determine the grams of water in the sample.
Mass of the sample =total mass*fraction
= 201*0.25
=50.25g

Experiment 1.

PART A
Measurement of Mass

1. Weigh a 100-mL beaker on a centigram balance and record the measurement in table “A”, below (remember a centigram balance measures to ± 0.01 g). Put a circle around the estimated digit in the measurement and determine the number of significant digits in the measurement. Note: A centigram balance measures to two decimal places.

2. Weigh the 100-mL beaker used in part “a” using a milligram balance and record the measurement in table “A” (remember a milligram balance reads to ± 0.001 g). Put a circle around the
estimated digit in the measurement and determine the number of significant digits in the measurement. Note: A milligram balance measures to three decimal places.

3. Repeat part “a” and “b” above, but this time using a 125 mL Erlenmeyer flask. Record your measurements in table A.

PART B
Determining the volume and the perimeter around face ABFE of the rectangular solid, shown in the diagram below.

Choose one of the vertices of the cube e.g. vertex B (Three edges meet to create a vertex). Measure the lengths of AB, BC and BF in centimeters, recording your measurements to the nearest +/- 0.01 cm in your data sheet.
Calculate the volume of the rectangular solid, showing your calculations in the space provided and reporting your answer to the correct number of significant digits.

Calculate the perimeter around face ABFE of the rectangular solid reporting your answer to the correct number of significant digits (perimeter means distance around face ABFE).

PART C
Calculating the density of a rectangular solid.

Your instructor will provide you with an unknown rectangular solid. Record the number or letter written on the rectangular solid. If your rectangular solid is a pure metal, record the symbol or name of the metal. Measure the length, width and thickness (height) of your rectangular solid in centimeters (note: your ruler reads to ± 0.01cm). Record your measurements in table B on your data sheets.
Weigh the rectangular solid on a centigram balance and record your mass to the nearest ± 0.01 g, in table B.
Calculate the density of your rectangular solid, reporting your answer to the correct number of significant digits and with the correct units.

Part D
Measuring volumes of liquids.

1. Fill a 100-mL measuring cylinder to the 100-mL mark with tap water and record its volume as
100.0 mL. Approximately, half fill a test tube with water from the cylinder and record the volume of the water left in the cylinder in table C. Remember a 100-mL measuring cylinder reads to ± 0.1 mL. Report the number of significant digits in each of the measurements you made, in Table C.

2. Select a 10-mL measuring cylinder that has 10 equal divisions per mL. Fill the 10-mL measuring cylinder to the 10-mL mark with tap water and record its volume as 10.00 mL. Approximately, quarter fill a test tube with water from the cylinder and record the volume of the water left in the cylinder in table C. Remember a 10-mL measuring cylinder reads to ±0.01 mL.
Report the number of significant digits in each of the measurements you made, in the Table C.

DATA SHEETS NAME: Matthew Ramirez
PART A: Measurement of Mass
TABLE A

GLASSWARE
Mass
Number of significant digits
Mass of 100 mL beaker obtained using a centigram balance 31.75148 3.175148 x 101
Mass of 100 mL beaker obtained using a milligram balance 31751.48 3.175148 x 104
Mass of 125 mL Erlenmeyer flask obtained using a centigram balance 28.3496 2.83496 x 101
Mass of 125 mL Erlenmeyer flask obtained using a milligram balance 28349.6 2.83496 x 104

PART B
Determining the volume of a rectangular solid and perimeter around one of the faces (ABFE).

Choose one of the vertices of the cube e.g. vertex B (Three edges meet to create a vertex).

1. Length of AB in centimeters: 8 cm

2. Length of BC in centimeters: 5cm

3. Length of BF in centimeters: 3 cm

4. Volume of rectangular solid: 12
120 ml

Show your calculation of the volume of the rectangular solid, in the space provided below, reporting your answer to the correct number of significant digits.

Perimeter around Face ABFE: 19 cm

Show your calculation of the perimeter around face ABFE, in the space provided above, reporting your answer to the correct number of significant digits.

PART C
Calculating the density of a rectangular solid.

:

TABLE B

Length of rectangular solid 8

Width of rectangular solid 5

Height (thickness)of rectangular solid 3

Mass of rectangular solid
200.00 g = 0.2 kg

Calculation of Density of rectangular solid ; D = g/ml,

g = 200
ml = 120
d= 200/120

Density of Rectangular = 1.667 g/ml

PART D
Measuring volumes of liquids.

TABLE C

VOLUME MEASUREMENT
Volume (mL) Number of significant digits

Volume of tap water in the P/measuring cylinder when it is filled to the 100-mL mark: 100.05 1

Volume of tap water left in the measuring cylinder after approximately half-filling a test tube: 50.00 0

Volume of tap water in the P/measuring cylinder when it is filled to the 10-mL mark: 10.0 0

Volume of tap water left in the measuring cylinder after approximately quarter-filling a test tube. 2.5 1

POSTLAB QUESTIONS NAME: Matthew Ramirez
(Note that all the numbers are measured numbers)

1. How many significant digits are there in each of the following measurements?

(a) 2688 cm = 4 (b) 3.507 g= 4

(c) 5.700 km = 2 (d) 0.00400 kg= 4

(e) 24.00300 m = 5 (f) 2400 m =2

(g) 9.5000 x 10-8 m = 9 (h) 0.0020056 g = 8

2. Round each of the following measurements to two significant digits.
(a) 0.00258 cm =0.0026cm (b) 28.23 g= 28 g
(c) 5.998 cm = 6.0 cm (d) 1.75 g = 1.8 g
(e) 1.05 g= 1.1 g

3. Do the following calculations and round your answer to the correct number of significant digits.

(a) 16.5 cm + 8 cm + 4.37 cm = 2.887 * 101 (b) 13.57 cm – 6.3 cm =
7.27

(c) 672 cm × 39.864 cm × 10 cm =2.6*10-5 (e) 13. 57 cm / 6.3 cm2 = 7.2*107

(f) (14.86 cm + 13.7 cm) × (65.346 cm – 4.10 cm)
= 1.6*10-2
(43.888 cm – 32.888 cm)

4. Write each of the following measurements using scientific notation.

(a) 0.000450300 m = 4.504 * 104 m

(b) 4567.67 g = 4.56767 * 103 g

5. Why are significant digits important when taking data in the laboratory?
It helps indicates the precision of the measured value to anybody who looks at the data

6. What is wrong asking about the number of significant digits in 4.56?

3 significant figures

7. Indicate how many significant figures there are in each of the following measured values.
a. 246.89 = 5
b. 107.856 = 6
c. 100.2 = 4
d. 0.646 = 3
e. 1.006 = 4
f. 0.005640 = 4
g. 14.600 = 5
h. 0.0002 = 1
i. 800000 = 6
j. 350.670 = 6
k. 1.0000 = 5
l. 320001 = 6
8. Calculate the answers to the appropriate number of significant figures.

a. 32.456 + 135.0 + 1.2345 = 168.69
b. 246.14 + 238.234 + 98.1 = 582.47
c. 658.0 + 23.34567 + 1345.29 = 2026.62

9. Calculate the answers to the appropriate number of significant figures.

(a) 24.7 × 1.8 = 4.446

(b) 45.65 × 0.25 = 1.14125

(c) 81.04 g × 0.010 = 8.104

(d) 6.47 × 63.7 = 4.12139

3.
(e)  5.73791

0.
(f) 1.678  2.23514286
0.

(g) (2.67×1012) × (3.7 × 104) = 9.879*1012
(h) 1.2X103/2.4X104
= 0.05

10. Round off the numbers to the indicated significant figures.

(a) 230 to one sig fig 230

(b) 2345 to three sig fig 2345

(c) 789000 to two sig fig 789000

(d) 6700 to one sig fig 6700

11. Convert the following numbers to scientific notation using significant figures.

a. 2340000000 2.3*109
b. 0.00034 3.4*10-4
c. 123000000 1.2*108
d. 0.000160 1.6*10-4

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