Lab Practical 1 (Units 1-6) Flashcards
Describe the base units of the metric system
Meter
Liter
Gram
Explain what metric unit is used to measure volume, length, mass, and temperature
Meter= length/distance Liter= volume Gram= mass Temperature= celsius
Know how to convert between metric units with the same base (move the decimal)
0.013 deciliters= 1,300,000 nanoliters
480,000 micrometers= .048 decameters
Know the metric prefixes, their abbreviations, and how much of the base unit they represent
T-Tera- 10^12 G- Giga- 10^9 M- Mega- 10^6 k- Kilo- 10^3 h- hecto- 10^2 da- Deka- 10^1 meters, liters, grams- 10^0 d- deci- 10^-1 c- centi- 10^-2 m- milli- 10^-3 u(kindof)- micro- 10^-6 n- nano- 10^-9 p- pico- 10^-12
Convert between different metric base units (1g=1ml=1cc) of water at standard conditions
freezing: 0 C = 32 F
Room Temperature: 21.1 C = 70 F
Body Temperature: 37 C = 98.6 F
Boiling: 100 C = 212 F
1 cc = 1 ml
1 ml = 1 g
1 liter = 1 kg
1 dm^3 = 1 liter
50 ml of water weighs 50 g
3 liters of water equals 3 kg
1 liter = 1000 ml
Describe how to convert from Fahrenheit to Celsius and how to convert from celsius to Fahrenheit
F to C
- F-32
- Multiply by 5
- Divide by 9
C to F
- C x 9
- Divide by 5
- Add 32
Identify all lab equipment used in unit 1
Graduated Cylinder Beaker Erlenmeyer Flask Triple Beam Balance Digital Balance/Scale Graduated Pipette (Pipette) Weigh Boat Hot/Stir Plate Stir Bar Pipette Pump Beaker Tongs Test Tube Tongs
Draw/define meniscus
When measuring the volume of a liquid in a graduated cylinder, you will observe a “meniscus.”
The meniscus is the curved upper surface of a liquid in a tube. You measure the liquid/volume from the bottom of the curve
(which is in the middle) of the meniscus.
Know which lab items are most accurate when measuring volume (2)
Graduated Cylinder
glass pipette
Know how to appropriately measure the mass using both the electronic balance and the triple beam balance
Digital/Electronic Balance/Scale
- Locate and place the weigh boat on the digital balance.
- “Tare” the digital balance in order to reset the balance to “0” grams. This will ensure that you do not add the weight of the weigh boat to what you are weighing.
Triple Beam Balance
- On the triple beam balance, you set the item on the metal pan without the weigh boat.
- Make sure it is set to zero by using the adjustment knob underneath the pan.
Understand if something should be measured in grams or kg
Grams are smaller than kilograms, so something smaller would be measured in grams.??
Know how to appropriately measure length using rules and meter sticks
Something smaller would use a ruler to find the length.??
Predict if an item would be appropriately measured in mm, cm, m, or km
Depends on the size of the item??
Distinguish between weight and mass
Mass is a measure of how much matter an object has.
Weight is a measure of how strongly gravity pulls on that matter.
Write numbers in scientific notation
0.000554433= 5.54433 x 10^-4 457430= 4.57430 x 10^5
Take a number in scientific notation and write in long form
- 11 x 10^-4= 0.000911
8. 992233 x 10^6= 8992233
Calculate the mean, median, and range of a set of numbers
Mean: an average of a group of measurements
add all values and divide by total number of values.
Median: the value that is in the middle of a group of measurements.
Arrange values in order from lowest to highest. Then pick the middle one.
If there are an even number of values, pick the two middle and add them together then divide that by 2.
Range: the difference between the smallest and the largest measurements.
Subtract the smallest value from the largest value.
Known the definition of deviation, variance, and standard deviation
Deviation: Measures hoe the measurements vary from the mean (+ or -). In other words, what is the difference between an actual measurement and the mean, or average, of the sample?
Variance: This measures how much difference, or variation, there is between the values you have obtained. The smaller the variance, the closer the values will be to the mean. Likewise, the larger the variance, the farther the values will be from the mean.
Standard Deviation: Standard deviation gives you an idea of the widely spread your values are about the mean. The smaller the standard deviation, the closer your values will be to the average. If you were to graph data having a small standard deviation, you would expect a tall, thin bell shaped curve. On the other hand, if the standard deviation were large, your bell shaped curve would be wider.
(((LOOK AT THE UNIT 1 LAB MANUAL TO SEE HOW TO CALCULATE THESE THINGS)))
Describe why a pencil looks yellow
A pencil looks yellow because the white light is hitting it and all of the colors are being absorbed, but the yellow light is being transmitted back out, which is what makes the pencil appear yellow.
Correlate colors of visible spectrum with their corresponding wavelengths or range of wavelengths
Red= 620-750 nm Orange= 590-620 nm Yellow= 570-590 nm Green= 500-570 nm Blue= 450-500 nm Violet= 380-450 nm
Identify components of a spectrophotometer
Digital Display Mode Button Sample Holder Wavelength Knob 0% T Knob 100% T Knob
Know how to calibrate the spectrophotometer to 0% and 100% transmission
- Adjust the wavelength control knob until the digital display shows 540 nm. (Make sure the filter level is in the correct wavelength range.)
- Make sure that you use the zero control knob to set transmittance to “0” before inserting your blank tube. Insert the “blank” into the sample holder and close the lid.
- Adjust the meter reading 100% transmittance using the transmittance control knob.
What is the purpose of a blank tube?
A blank tube is a tube that is used in the spectrophotometry experiments that cancels out any unwanted molecules from absorbing light.
Describe the inverse relationship between transmittance and absorbance
As the amount of light transmitted by a solution increases, the amount
of light absorbed might be expected to decrease proportionally.
(((??the light absorbed by a solution depends on the absorbing ability of the
solute, the distance traveled by the light through the solution, and the concentration of the solution.??))
Transmittance measures how much light passes through the sample.
Absorbance measures how much light is absorbed by the substance.
What does it mean when there is nothing in the spectrophotometer and you are setting 0% transmission (think about absorbance)?
At this point, no light is shining on the detector. This step ensures that the measuring scale reads 0 under these conditions.
What does it mean when there is only the blank tube in the spectrophotometer and you are setting 100% transmission (think about absorbance)?
By setting the scale on the spectrophotometer to 100% transmittance using this “blank,” you can distinguish between light absorbed by your sample and light absorbed by your “blank” tube.
Define serial dilution and know how to create a serial dilution
A serial dilution is the repeated dilution of a solution to achieve a geometric dilution of the original solution.
To create a serial dilution you remove small amounts of an orignal solution to another container with a solution. Then you keep repeating and remove a small amount from that one to the next one, and then take a small amount from that one and then move to the next, and so on.
If given the starting concentration of a serial dilution, understand how to determine the concentration of each subsequent dilution
If you want to determine the concentration of a substance in a particular dilution, you multiply the original concentration times the dilution.
To illustrate consider the following:
Example 1:
You had a solution with 4 g of glucose per mL. You dilute this original solution by adding 1 mL of it to 9 mL of water. What is the dilution you prepared?
By adding 1 mL of solution to 9 mL of water, you have prepared a 1:10 dilution. Therefore:
4 g/mL x 1/10 = 4 g/mL/10 = 0.4 g/mL
Example 2:
If you had a 100 mg/dL solution of glucose and made a 1:5 dilution, what concentration of glucose is contained in the dilution?
100 mg/dL x 1/5 = 100 mg/dL/5 = 20 mg/dL
Describe the relationship between protein concentration and absorbance
Protein concentration and absorbance can be used to find one of those if you don’t know the other one of a solution of something. They are proportional to each other.
Know how to construct a standard curve
Ton construct a standard curve, you plot the absorbance of each dilution on the Y-axis against the concentration of each dilution on the X-axis. You will draw a line of best fit using the data points you plot. By drawing a straight line from (a) to the curve at (b) and dropping from the curve to (c), the concentration of an unknown solution can be determined.
Understand how to use a standard curve to find the concentration of an unknown protein solution (Fig 3.1)
You can find the concentration of an unknown solution if you know the protein concentration and absorbance of some solutions. To find the unknown solution’s concentration, you plot the absorbance of each dilution on the y-axis against the protein concentration of each dilution on the x-axis. Then you draw a line of best fit using the data points you plotted. Then you take the absorbance of the unknown and plot it on the y-axis, and then draw a straight line from that point to the curve/line of best fit that you drew through the points plotted. Then you draw a straight line down from the point where the line hit the line of best fit (which ends up looking like a squareish object). Then where the line hits on the x-axis will give you the protein concentration of that solution.
Know the flow of the scientific method (Sup Fig 1)
Observe —> hypothesize —> experiment —> analyze/conclude
Define independent and dependent variable
Independent Variable: The variable in an experiment that is being manipulated by the researcher.
Dependent Variable: The variable in an experiment that has the potential to change in response to the experimental conditions altered by the researcher. The dependent variable is often times is defined as the variable that changes in response to the independent variable. It depends on the independent variable.
Identify the independent and dependent variable in scientific protocols
Independent: the value you are manipulating
Dependent: products produced by the reaction
Define hypothesis
A hypothesis is not an educated guess, but instead is a statement based off of previously supported data. A hypothesis must be falsifiable, and therefore must provide a means to test and either support or nullify the hypothesis. Note that one does not “prove” a hypothesis as being true, but instead determines whether or not the hypothesis is supported by the data obtained from experiments.
Describe the relationship between H+ concentration and pH
The pH of a solution is defined as the negative logarithm (base 10) of the hydrogen ion concentration. pH= -log [H+]
pH declines as the H+ concentration increases.
Explain what an acid or a base does to the H+ concentration of a solution
An acid is a substance that increases the H+ (hydrogen ion) concentration of a solution.
A base is a substance that reduces/decreases the H+ (hydrogen ion) concentration of a solution.
