Paper chromatography and Basic safety

What is adsorb:

To stick to the surface of either a solid or liquid

Chromogenic meaning and reagents used in experiment? What does chromogenic reagents do?

Greek origin for color; ammonia, dimethylglyoxime, and Hydrogen peroxide. Chromogenic regents help make spot more visible.

What is Rf formula?

(spot distance) / (solvent distance)

What does Rf Stand for

retention Factor

How many Spots in Colums, F and U

F - 5 & U-3

how many Spot should be in each columns? (A-e)

1 spot

Two effects which cause a metal ion to have a high rf?

Very soluble solvent & weekly absorbed onto paper

Proper way to dispose of capillary tubes and solvent

Tubes grow in broken glass container; Solvent goes down the sink with lots of water

why do we need to stop chromatography before solvent reaches the top edge of paper

We need the solvent line to get the RF value

what chemicals need to be covered for experiment to Succeed.

Acetone- highly flammable & hydrochloric acid- causes irritation to eyes

In all, chemical evaporates if not covered

Two different students performed paper chromatography on an unknown metal ion using identical experimental conditions. "Student A" removed his paper when the solvent front had traveled 3.00 cm up the page while "Student B" allowed her solvent front to travel 5.00 cm. Will Student B's R, value be higher, lower, or the same as Student A's R, value? EXPLAIN why you reached this conclusion

even though one runner (chemical) went further, the steepness of the hill (how the paper absorbs) is the same for both, so they will both have the same measurement of how far up the hill they got (Rf value)

Suppose that you discovered two different ions had the same R, value in this experiment. What

could you change about the experiment in order to separate them into two spots with different R, values? (Note: you can't change the ions

A paper with different absorbency properties could influence how the ions interact with the stationary phase.

CU 2+ & ammonia (NH3) to make a dark blue colored chemical species

Cu2+(aq) + 4NH3(aq) + Cu(NH3)42+(aq)

Ni2+ and ammonia to make a pale violet chemical species.

Ni²⁺(aq) + 6NH₃(aq) ⇆ Ni(NH₃)₆²⁺(aq)

The reactions involving hydrogen peroxide and Mn(OH)2 to make a dark brown chemical.

Mn(OH)2 + H2O2 → MnO2 + 2H2O

Chemical formula for the NI(DMG)₂ complex ( the red color you see for the nickel spot)

C₈H₁₄N₄NiO₄

What is paper chromatography?

technique to separate and identify components of a mixture to find unknown mixtures.

Are pipets best clean by placing the top in under a faucet and letting water flow through the pipet?

No, False

Percent error is a tool to measure accuracy.

True

What does TD and TC mean on laboratory glassware?

Td-To deliver TC- To Contain

Why is it inadvisable to place objects that are hot on a balance?

Causes inaccuracy for what is being measured

What is the definition of density that can be determined from a single unit?

The ratio of the mass of an object to its volume. D=m/v; You need two data points to determine measurement.

What is the difference between precision and accuracy? what mathematical tool is a test for precision? what mathematical tool is a test for accuracy?

P: is a measure of how data are to each other.( standard deviation)

A: is a measure of how data are to the true value. ( percent error)

Most precise to least precise (Graduated cylinder, repipet, pipet)

Graduated cylinder < repipet < pipet

Most accurate to least precise (Graduated cylinder, repipet, pipet)

Repipet <Graduated cylinder< Pipet

Why is Dmg Important

DMG detectects the nickel cation forming a birght red spot

Why is ammonia important

this makes the separated components more visible on the paper. Making CU²⁺ appear dark blue. Also, Ni²⁺ appear pale violet.

H₂O₂ (Hydrogen peroxide)

It causes Mn²⁺ to be visible.

What is meant by Rf and what information is needed to calculate an Rf value

you need the distance the spot moved (cm)/ distance the solvent front moved (cm)

What is the maximum and minimum value for Rf

Minimum: 0, maximum: 1