Investigation 2: Investigation 2: Part 2-Citric Acid SaturationPart 2-Citric Acid Saturation

What is citric acid?What is citric acid?

Citric acidCitric acid is a weak is a weak organicorganic acidacid found in found in citrus fruitscitrus fruits. It is a natural . It is a natural preservativepreservative and is also used to add and is also used to add an acidic (sour) taste to foods and an acidic (sour) taste to foods and soft drinkssoft drinks. .

How can you find out if citric acid How can you find out if citric acid dissolves in water to make a dissolves in water to make a solution?solution?

If it does dissolve, how can you find If it does dissolve, how can you find out how much citric acid is needed to out how much citric acid is needed to saturate 50 ml of wanter?saturate 50 ml of wanter?

ProceduresProcedures

Work in pairs. Each group will get two bottles, Work in pairs. Each group will get two bottles, but only one citric acid supply, syringe, and but only one citric acid supply, syringe, and funnel.funnel.

Put 50 ml of water (one syringe) into each of Put 50 ml of water (one syringe) into each of the bottles. Then return the water and the bottles. Then return the water and syringe to materials station.syringe to materials station.

Put a sticky note on the bottle, with the Put a sticky note on the bottle, with the bottom of the note right at the water level. bottom of the note right at the water level. Use a bit of tape to secure the label.Use a bit of tape to secure the label.

Add citric acid one spoon at a time. Shake Add citric acid one spoon at a time. Shake the bottle until the citric acid dissolves. Then the bottle until the citric acid dissolves. Then add another spoon of citric acid.add another spoon of citric acid.

New ConceptNew Concept

Solubility-how much of a material Solubility-how much of a material dissolves in a liquiddissolves in a liquid

Were you able to dissolve more salt Were you able to dissolve more salt or citric acid in water?or citric acid in water? Citric acid is more soluble than salt in Citric acid is more soluble than salt in

water.water. This means that more scoops of citric This means that more scoops of citric

acid can fit into 50 ml of water, than acid can fit into 50 ml of water, than salt.salt.

How much citric acid dissolved?How much citric acid dissolved?

How can we find out how many How can we find out how many grams of citric acid it took to grams of citric acid it took to saturate 50 ml of water?saturate 50 ml of water?

Procedures for Finding out How Procedures for Finding out How Much Citric Acid was DissolvedMuch Citric Acid was Dissolved

Place a labeled cup under the funnel.Place a labeled cup under the funnel. Filter the solution using a Filter the solution using a wet filter paperwet filter paper. The . The

saturated solution will pass through the filter; the saturated solution will pass through the filter; the undissolved salt won’t.undissolved salt won’t.

Place the saturated salt solution on one side of Place the saturated salt solution on one side of the balance and 50 ml of plain water on the other the balance and 50 ml of plain water on the other side.side.

Add gram weights to the plain water to achieve Add gram weights to the plain water to achieve balance. The amount of mass added to the water balance. The amount of mass added to the water is equal to the mass of salt dissolved in the is equal to the mass of salt dissolved in the saturated salt solution.saturated salt solution.

Record the number of grams of salt it takes to Record the number of grams of salt it takes to saturate 50 ml of water.saturate 50 ml of water.