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Why do solutions change color?

Why do solutions change color?

Tell students that when an acid is added to an indicator solution, the acid donates protons to the water molecules. This increases the concentration of H3O+ ions in the solution. The H3O+ ions donate protons to the indicator molecules causing the indicator to change color toward red.

What causes color change in chemical reactions?

When two or more substances combine, they create one or more new substances, which sometimes have different molecular structures from the original substances, meaning they absorb and radiate light in different ways, leading to a color change.

What is the purpose of the Bromothymol blue BTB solution?

Bromthymol Blue is a dye used as an indicator in determining pH. Bromthymol blue is a weak acid. It can be in acid or base form, depending on the pH of the solution. This reagent is yellow in acidic solutions, blue in basic solutions and green in neutral solution.

What was the initial color of the bromothymol blue solution?

Bromothymol blue (BMB) is an indicator dye that turns yellow in the presence of acid. When carbon dioxide is added to the solution, it creates carbonic acid, lowering the pH of the solution. BMB is blue when the pH is greater than 7.6, green when the pH is between 6-7.6, and yellow when the pH is less than 6.

How do you make Bromothymol blue?

Combine 20 mL of alcohol to the sodium hydroxide/bromothymol blue solution. Dilute the mixture with 1 L of distilled water in a large container. The solution should be dark blue in color. If the solution appears green, use a pipette to slowly add sodium hydroxide drop by drop to the solution until it changes to blue.

What does yellow BTB mean?

BTB is an acid indicator; when it reacts with acid it turns from blue to yellow. When carbon dioxide reacts with water, a weak acid (carbonic acid) is formed (see chemical reaction below). The more carbon dioxide you breathe into the BTB solution, the faster it will change color to yellow.

How do you take Bromothymol blue?

Bromothymol blue is used to measure the pH of solution based on the color change of the solution. It is prepared by dissolving bromothymol blue powder in sodium hydroxide and then diluted in water and possibly alcohol. In basic conditions it is blue while acidic conditions it is yellow.

Does lime turn blue litmus red?

Lime juice is acidic in nature so it can turn blue litmus paper to red while the alkaline solution can turn the red litmus paper blue.

Why is lime water basic in nature?

Answer. Lime juice is the juice obtained from lime, a citrus fruit. On the other hand, lime water is a saturated solution of a base called calcium hydroxide (chemical formula Ca(OH)2) in water. Hence, lime water is not acidic but basic in nature.

Why does exhaled air make the Limewater Milky Class 7?

Turns lime water to milky because of the carbondioxide from the exhaled air. The carbon dioxide in our exhaled air reacts with the calcium hydroxide in the lime water to produce calcium carbonate which is milky in colour.

Why the lime water turns milky when we exhale into the lime water?

To test the presence of carbon dioxide in the exhaled air, take some freshly prepared lime water in a test tube. We know that lime water turns milky when carbon dioxide gas is passed through it. Since lime water turns milky due to the exhaled air, we conclude that the exhaled air contains carbon dioxide.

How can we prove that we exhale carbon dioxide?

If you will exhale in the limewater, it will turns to milky if CO2 is there…that will give you the proof that we exhale CO2 gas.

How can we detect the presence of CO2?

A standard test for the presence of carbon dioxide is its reaction with limewater (a saturated water solution of calcium hydroxide) to form a milky-white precipitate of calcium hydroxide. Carbon dioxide occurs in nature both free and in combination (e.g., in carbonates).