Red vs Blue Litmus Papers
Indicators are a special type of chemicals, which have the ability to change their colors when pH is changing. Therefore, these are known as pH indicators. Some indicators can take different colors to different pH values. For example, pH papers show a range of colors depending on the strength of acidity and the basicity of the medium. Indicators like phenolphthalein only change its color to show that the medium is acidic or basic. It does not give an idea about how acidic or basic is the medium (but the intensity of color may slightly vary in low and high basic mediums). For instance, in acidic medium phenolphthalein is colorless and in basic medium, it is pink in color. Other than the synthetic chemicals, there are natural indicators too. For example, red cabbage can be taken. Indicators come as various forms like powders, liquids, paper stripes, etc. Depending on the requirements, these can be selected. For example, to indicate the end point of an acid base titration, an indicator in the solution form is ideal. To determine the pH of a reaction mixture, we can use pH papers or litmus papers. Further, indicators have different pH ranges where they can function as an indicator. Phenolphthalein has the pH range of 8.3-10, so it is changing its color in basic pHs. As you can know, pH indicators are essential for a chemical lab. They are easy to handle and use, give instantaneous readings and most of the time readings are accurate.
Litmus paper is an indicator, which can be used to determine acidic and basic solutions. Normally this comes as a paper stripe. Mixture of water-soluble dyes extracted from lichens like Roccella tinctoria is absorbed into filter paper stripes, to make litmus paper. In this mixture, there are about 10- 15 types of dyes. There are two types of litmus papers as blue and red.
Red Litmus Paper
Red litmus paper is used to test basic solutions. Red litmus papers turn blue when encountered with a basic solution. The neutral litmus papers are purple in color. The color change of litmus papers is taking place over pH range 4.5-8.3 at 25 °C. Therefore, one of the disadvantages of litmus papers is that they cannot be used to determine the pH value. The strength of the acidity or the basicity also cannot be determined using litmus papers. On the other hand, the readings are instantaneous, and easy to take. Litmus papers can be used by anyone without any expertise knowledge. They only have to know which color is relevant to acidic and basic pH value.
Blue Litmus Paper
Blue litmus paper responses to acidic solutions as like red litmus paper changes its color to blue in the basic / alkali medium. When a drop of an acidic solution is placed in the blue color litmus paper stripe, it turns to red.
What is the difference between Red Litmus Paper and Blue Litmus Paper?
• As the name depicts, red litmus papers are red in color, and blue litmus papers are blue in color.
• The main difference of them is their reaction to different pH values.
• Red litmus papers react to basic solutions, whereas blue litmus papers react to acidic solutions.
• Red litmus changes its color to blue in basic medium, whereas blue litmus changes its color to red in acidic medium.