Table of Contents
Why do bases change the color of indicators?
When a base is added to an indicator solution, it accepts protons from the water molecules, creating OH− ions. The H3O+ ions and indicator molecules donate protons to the OH− ions, causing the indicator to change color toward purple.
Why does an indicator shows different Colours in acidic and basic media?
Acidic indicator is represented by Hin. In acidic solution, the equilibrium shifts towards left. Hence, an acidic indicator has the colour of HIn in acidic solutions. In basic solution, the equilibrium shifts towards right ans shows colour of In – in alkaline solution.
What causes an indicator to change color and how it is used in an acid base titration?
As base is added the pH will increase, causing the indicator to change to its basic (In-) form, causing a visible colour change. The point in the titration at which the colour changes is known as the endpoint of the titration.
What constituent of acids is responsible for changing the color of the litmus paper?
Red litmus contains a weak diprotic acid. When it is exposed to a basic compound, the hydrogen ions react with the added base. The conjugate base formed from the litmus acid has a blue color, so the wet red litmus paper turns blue in alkaline solution.
Do both acids and bases change colour of all indicators?
Answer: (a) Only (iv) All indicators do not change colour with acids as well as bases, e.g. turmeric changes its colour to pink with base but it remains yellow with acid.
What is the colour change for red litmus indicator for acids and bases?
The main use of litmus is to test whether a solution is acidic or basic, as blue litmus paper turns red under acidic conditions, and red litmus paper turns blue under basic or alkaline conditions, with the color change occurring over the pH range 4.5–8.3 at 25 °C (77 °F).
What is the colour change for below indicator for acid and bases blue litmus red litmus phenolphthalein turmeric?
Colour of litmus paper in acid: Blue litmus paper turns into red when dipped in acidic solution. Colour of litmus paper in base: Red litmus paper turns into blue when dipped in basic solution. Turmeric: Turmeric is also used as natural indicator. Turmeric is of yellow colour.
Why does acid turn blue and red litmus?
Blue litmus paper turns red under acidic conditions and red litmus paper turns blue under basic (i.e. alkaline) conditions. The pigment in blue litmus reacts with H+ ions and changes chemically so the bonds are ‘tuned’ to reflect a longer wavelength of light to appear red to our eyes.