Chemistry Unit 1 and 2 Test

Question 1

N=? of Na2CO3 w/ 0.6003g of NA2CO3 dissolved in 500.00mL of water. M.W.= 105.989g/mol

Answer 1

eq=2

M=0.6003g/ 105.989g =0.005664
M= 0.005664/0.50000
= 0.0113 mol/L

N=2x 0.0113
=2.27x10^-2

Question 2

Prior to going sampling, what are major steps to do?

Answer 2

1) Decontaminate your equipment
2) Add preservatives into bottles and label

Question 3

Soil and Veg main step to extract Zn?

Answer 3

1) Crushing and Grinding sample (Pre step)
2) Use appropriate acid to digest for Zn.
- mixture 3:1 Hydrochloric acid, Nitric acid = aqua regia

Question 4

How do you define light?

Answer 4

1) Light is about electrons on the outer most layer away from the nucleus only.
2) When electrons try to reach the ground level which than releases photons.
3) It is electron megnetic wave, Quanta, and has jule properties.

Question 5

What is the wave length in nm when the frequency v=7.15x10^14 Hz and the speed of light c=3.00x10^8 m/s

Answer 5

WL= c/v
=3.00x10^8 x 10^9
=420 nm

1m=10^9nm
1nm= 10^-9 m

Question 6

Beers Law
A= 0.908
T=?
%T=?

Answer 6

T= 10^-A
=10^(-0.908)
=0.1236

%T= 12.36%

Question 7

WL=?nm
E=8.43x10^19 J
h=6.626x10^-34 J/s
c=3.00x10^8 m/s

Answer 7

E=h*(c/WL)

WL=(hc)/E
=(6.626x 10^-34 3.0010^17)/ 8.4310^-19
=236nm

Question 8

What is the importance of statistics for sampling?

Answer 8

1) Used to compare other samples through time and space.
2) to know how accurate or inaccurate you are. (to determine certainty or uncertainty because any measurement without uncertainty is meaningless.
3) helps you to know what you are analyzing exactly through rational. “know what you are doing”.

Question 9

when you have a chemical?

Answer 9

you need to know its Wavelength at maximum absorbance.

Cx=?

C=unknown
x= chemical is known

Question 10

Concentration of analyte given?

C=?
T=70.3%
A=?
ε=8382 L mol-1 cm-1
L=1.00

Answer 10

Molar absorptivity =ε

1) A=-log(0.703)
=0.153

2) C= A/ (εL)
=0.153/(83821.00)
=1.83*10^-5

Question 11

Lambert Beers Law?

Answer 11

1)Understanding the interaction between light and matter. (absorbance or transmittance vs Concentration)
2)We need color to analyze molecules, atoms, metals, and concentration.
3) Based on color intensity- it will describe the main components of a spectrophotometer.
-sources
-monochromators( depends on what light wanted)
-detectors.

Question 12

Spectroscopy

Answer 12

Study of interactions between matter and radiated energy.

ex. metal turning red from heat. and it is used for atoms.

Question 13

Spectrometry

Answer 13

Implicates quantitative measurements of light intensity as a function of wavelength.

ex. large molecules

Question 14

Spectroscope

Answer 14

Disperses the light to see the components of visible light

Question 15

Spectrometer

Answer 15

Permits the quantitative measurements of that dispersed light

Question 16

Spectrochemical Analysis

Answer 16

used to identify and/or measure chemicals in a sample

Question 17

Highest energy to lowest energy?

Answer 17

1) UV
2)Visible domaine
3)Infrered

Question 18

Gama?

Answer 18

really close wave lengths, highest energy

Question 19

when energy of light increases…

Answer 19

wave length will decrease

Question 20

safest wavelength

Answer 20

Radio wave, no gama, you can catch easily. “big foot(big wave)

Question 21

Gale Galelaeo

Answer 21

First person to measure light, did not succeed.

Question 22

Speed of light equation

Answer 22

c=WL*V

Question 23

Visible light range

Answer 23

700- 400nm

700 starts at red, lowest energy
400 has the most energy, blue

Question 24

Large wave length?
Small wave length?

Answer 24

LWL: Radio wave, phones, microwave.

SWL: Infrared, UV, Heat lamps

Question 25

V of blue light is 6.3*10^14Hz

convert to KHz and MHz

Answer 25

KHz= 10^-3
=6.310^11
MHz= 10^-6
=6.310^8

Question 26

Planck’s constant

Answer 26

h=6.626*10^-34 jule/sec

Question 27

Newton?

Answer 27

First person to use pyramid to disperse light

Question 28

Les pascal?

Answer 28

said light is not one light, it is a combination of light. Newton disagreed and than agreed.

Question 29

Wave number =

Answer 29

v with a dash on top

=1/ wave length

Question 30

Radiating Energy at
E=8.6x10^-21 joules
WL=?
v=?

speed of light is always 3.00*10^8m/s

Answer 30

E=h*v

v=E/h
=8.610^-21/ 6.62610^-34
=1.30*10^13Hz

WL= c/v
=(3.0010^8)/ 1.3010^13
=(2.31*10^-5) 10^9
=2.3110^4nm

Question 31

Rational for choosing a sample site?

Answer 31

1)ensure sample is representative for the sample.
2)ensure the sample is 50 meters away from water when looking for Zn.
3)ensure there is enough sample for the measurements you need.

Question 32

Spectro?

Answer 32

Spectroscopist not spectrometrist

Question 33

longest WL
Highest V

Answer 33

1)radio
2)x-ray

Question 34

what 5 questions should we consider when sampling?

Answer 34

1)where
2)what type
3)minimum amount of sample to need to collect for analysis
4)how many samples should we analyze
5)how can we minimize the overall varience for analysis

Question 35

Judgemental sampling

Answer 35

Judgmental sampling is more biased than random sampling, but requires fewer samples. Uses previous study.

Question 36

Systematic Sampling

Answer 36

systematic sampling we sample the target population at regular intervals in space or time.

it follows a pattern

Question 37

Systematic–Judgmental Sampling

Answer 37

systematic–judgmental sampling, in which we use prior knowledge about a system to guide a systematic sampling plan.

Question 38

Stratified Sampling

Answer 38

Stratified sampling is a sampling method that divides a population into smaller groups or strata based on common characteristics in the population data.

Question 39

Convenience Sampling

Answer 39

Convenience sampling is a non-probability sampling method where data is collected from an easily accessible and available group of people. (e.g. grab sample)

Question 40

Random sampling

Answer 40

Simple random sampling is a statistical method where every item in a population has an equal chance of being selected into a sample.