chemical engineering calculations

Question 1

general expression of a characteristic of measurement

Answer 1

dimensions

Question 2

example of dimensions

Answer 2

length, time, mass, temperature

Question 3

means of explicitly expressing the dimensions

Answer 3

units

Question 4

examples of units

Answer 4

feet, cm, hours, seconds

Question 5

what is an event that shows how important conversion is

Answer 5

a first officer had confused 1,500 meters (4,900 ft) with 1500 ft (460 meters), causing the pilot to make the wrong decision to descend because of the confusion with the altitude

Question 6

most commonly adopted system of units

Answer 6

SI (Le Système Internationale d’Unités)

Question 7

it uses a factor of 10 to convert one unit to another

Answer 7

SI

Question 8

what is the other name for the American engineering system in the system of units

Answer 8

English or imperial system

Question 9

much harder to convert one unit to another if we use this system

Answer 9

American engineering system

Question 10

it can be measured independently and is sufficient to describe most quantities

Answer 10

fundamental dimensions/units

Question 11

formed by combining the fundamental units through multiplication, division, or other mathematical operations

Answer 11

derived dimensions/units

Question 12

system of units

Answer 12

• SI
• American Engineering System
• centimeter-gram-second (cgs) system of units
• foot-pound mass-second (fps) system of units

Question 13

importance of attaching units

Answer 13

• diminish the possibility of errors in calculations
• reduce intermediate calculations and time in problem-solving
• have a logical approach to the problem rather than remembering a formula and substituting numbers into it
• have an easy interpretation of the physical meaning of the numbers you use

Question 14

the process of changing a measurement from one unit of measurement to another while maintaining the same quantity or value

Answer 14

unit conversion

Question 15

method used to analyze the relationship between physical quantities

Answer 15

dimensional analysis

Question 16

method used to derive formulas, check the correctness of equations, and convert units by using their dimensions

Answer 16

dimensional analysis

Question 17

ensures that all terms in an equation have the same dimensions, making the equation physically meaningful

Answer 17

dimensional consistency/homogeneity

Question 18

steps in dimensional analysis

Answer 18

• identify dimensions
• check for homogeneity
• derive equations

Question 19

a way of expressing numbers that are very large or very small in a concise and standardized format

Answer 19

scientific notation

Question 20

usually expressed as a product of a number and a power of 10

Answer 20

scientific notation

Question 21

general form of scientific notation

Answer 21

N = M x 10^n

Question 22

what is M in the general form of scientific notation

Answer 22

decimal number (mantissa) where -10<M<= -1 or 1=>M>10

Question 23

what is n in 10^n in the general form of the scientific notation

Answer 23

exponent (must always be an integer)

Question 24

for a very large number, the exponent is

Answer 24

positive

Question 25

for a very small number, the exponent is

Answer 25

negative

Question 26

it refers to the digits in a number that are meaningful in expressing its precision

Answer 26

significant figures

Question 27

includes all the certain digits and the first uncertain digit in a meaurement

Answer 27

significant figures

Question 28

conveys the level of accuracy and reliability in a measurement or calculation

Answer 28

significant figures

Question 29

rules of significant figures

Answer 29

- non-zero digits are significant - zeros between non-zero digits are significant - zeros before the first non-zero digit are not significant; they only serve to locate the decimal point - zeros after the decimal point at the end of a nonzero digits are significant - trailing zeros in a whole number may or may not be significant

Question 31

importance of significant figures

Answer 31

- reflect measurement precision - avoid overstating accuracy - maintain consistency in calculations

Question 32

in the multiplication or division operations in significant figures, the result should have the same number of significant figures as the factor with the

Answer 32

fewest significant figures

Question 33

in the addition or subtraction operations in significant figures, the result should have the same number of decimal places as the term with the

Answer 33

fewest decimal places