What is the purpose of water in ink chromatography?

Asked By: Cleofe Ayachi | Last Updated: 22nd January, 2020
Category: science chemistry
4.4/5 (2,262 Views . 9 Votes)
When ink is exposed to certain solvents the colors dissolve and can be seperated out. When we expose a piece of paper with ink on it to a solvent, the ink spreads across the paper when the ink dissolves. Some inks are water-soluble, so you can use water as the solvent.

Click to see full answer


Also, what is the purpose of the water in chromatography?

1 Answer. Chromatography is a technique used to separate the components of a mixture. Different solvents will dissolve different substances. A polar solvent (water) will dissolve polar substances (water soluble ink in the video below).

Additionally, what is the main purpose of chromatography? The purpose of chromatography in general is to separate molecules based on differences in size, charge or polarity, and solubility. Paper chromatography is no different; it uses paper as the stationary phase and a solvent as the mobile phase.

Similarly, you may ask, why is ink not used in chromatography?

The resins and colouring agents are miscible with other polar organic solvents that we use in the chromatography. So the ink also travels along with the mobile phase. Hence, a paper or sketch pen should never be used to draw a line either on Paper chromatography or a TLC sheet.

Is water always a good solvent in ink separation?

Diverse solvents can be used in ink chromatography. For inks that are water soluble, water is the solvent of choice. For inks that are not soluble in water, methanol, ammonium hydroxide, ethanol, acetone, or hydrochloric acid can be used as solvents.

37 Related Question Answers Found

Why is water not used in paper chromatography?

Technically it can, but it almost always isn't because the idea is to seperate out compounds based on their solubility in different types of solvents. Cellulose (paper) is polar and water is obviously quite polar, so there's no difference there by which to seperate out the compounds.

What is Rf value?

The Rf value is defined as the ratio of the distance moved by the solute (i.e. the dye or pigment under test) and the distance moved by the the solvent (known as the Solvent front) along the paper, where both distances are measured from the common Origin or Application Baseline, that is the point where the sample is

Why is ethanol better than water in chromatography?

But for dyes that are not water soluble, you'd use an organic solvent such as alcohol to dissolve them. So the only reason why you use alcohol rather than water is because your ink is soluble in ethanol but not in water. However, typically they will not move freely with the solvent all the time.

How will you use this procedure to identify an unknown type of colored pigment?

It is used in the sequencing of DNA and RNA. Paper chromatography is used as a qualitative analytical chemistry technique for identifying and separating colored mixtures like pigments. It is used in scientific studies to identify unknown organic and inorganic compounds from a mixture.

What is meant by polar and nonpolar solvents?


Polar solvents have large dipole moments (aka “partial charges”); they contain bonds between atoms with very different electronegativities, such as oxygen and hydrogen. Non polar solvents contain bonds between atoms with similar electronegativities, such as carbon and hydrogen (think hydrocarbons, such as gasoline).

What is the mobile phase?

mobile-phase. Noun. (plural mobile phases) (chemistry) The liquid or gas that flows through a chromatography system, moving the materials to be separated at different rates over the stationary phase.

Why does paper chromatography happen?

In paper chromatography, substances are distributed between a stationary phase and a mobile phase. The unequal solubility causes the various color molecules to leave solution at different places as the solvent continues to move up the paper. The more soluble a molecule is, the higher it will migrate up the paper.

What is the basic principle of paper chromatography?

Principle of paper chromatography: The principle involved is partition chromatography wherein the substances are distributed or partitioned between liquid phases. One phase is the water, which is held in the pores of the filter paper used; and other is the mobile phase which moves over the paper.

What pigments are in black ink?

Dye-based black ink
Dye-based black inks use colorants that are fully dissolved into a liquid (like water or oil). Most black dye-based inks include a combination of black dye and additional cyan, magenta, and yellow (CMYK. External Link. Opens in new window.)

How do you separate the components of ink?


Through the submersion of chromatography paper into water, any sample of ink can be separated into its respective cyan, magenta, and yellow components. The water causes the ink molecules to "travel" up the paper strip.

How would you separate the dyes of an ink?

Ink is a mixture of several dyes and therefore we can separate those colors from one another using chromatography. When ink is exposed to certain solvents the colors dissolve and can be seperated out. When we expose a piece of paper with ink on it to a solvent, the ink spreads across the paper when the ink dissolves.

What happens to black ink in chromatography?

When the water passes through the black ink marks it takes the pigment colors with it. So, as the water travels it separates the colors. This is called chromatography - separating the parts of a mixture so that you can see them one at a time. Black ink actually looks like a rainbow!

What causes the colors to separate in paper chromatography?

As the water creeps up the paper, the colors will separate out into their components. Capillary action makes the solvent travel up the paper, where it meets and dissolves the ink. The dissolved ink (the mobile phase) slowly travels up the paper (the stationary phase) and separates out into different components.

What are the ingredients in ink?

Ink made with color usually includes the following ingredients: petroleum distillate solvent, linseed oil, some form of organic pigments, and soybean oil. Inorganic pigments are not commonly used.

Why is water a good solvent in paper chromatography?


Answer and Explanation: The solvent is the mobile phase in paper chromatography which is very polar. Thus, due to less difference in polarity between the mobile and stationary phases, water may get bound to the surface of the stationary phase and not move up to separate non-polar solutes.

Why is a start line drawn in chromatography?

Answer and Explanation: In paper chromatography, the starting line must be drawn with the help of pencil because the pencil lead does not dissolve in solvent, thus it will not affect the separation. The spots of the compounds are separated correctly.

How is ink used in chromatography?

To perform ink chromatography, you put a small dot of ink to be separated at one end of a strip of filter paper. This end of the paper strip is placed in a solvent. The solvent moves up the paper strip and, as it travels upward, it dissolves the mixture of chemicals and pulls them up the paper.