Percent Composition Lab
Percent Composition Lab
Purpose: To determine the percent composition of sodium bicarbonate and sand in a heterogeneous mixture.
Background Information: Heterogeneous mixtures are mixtures that contain two or more pure substances that can be distinguished by sight. These substances have different physical and chemical properties which can be used to separate them.
Percent composition is the amount of a substance in a mixture compared to the whole mixture
Hypothesis: Not applicable
Materials & Equipment:
mixture (5-10g per group) stirring rod filter paper
funnel hot plate 250ml or 400ml beaker
beaker tongs insulated gloves watch glasses(can cover beaker)
rubber policeman electronic scale vinegar
evaporating dishes
Procedure:
The total mass of the sand and baking soda mixture is 13.403 grams.
Finding the Mass of the Baking soda: Add 5 ml (5.48 grams) of vinegar to the mixture to liquefy baking soda. Weigh the total mass of both the vinegar and baking soda the mass is 11.213 grams. Subtract the mass of the vinegar from the mass of the total solution to find the mass of the baking soda. The mass is 6.065 grams.
Finding the mass of the sand: Before you find the mass of the baking soda, and after you liquefy the baking soda, you need to use a filter paper and a funnel to separate the vinegar and baking soda solution from the sand, after you separate the sand from the vinegar and baking soda solution scrape the sand into a watch glass using the stirring rod. Put the watch glass and the sand on the hot plate to vaporize all the liquid from the sand. Wait. After your sand looks like sand and resembles no liquid in sight pour the sand on the evaporating dish which has a mass of 39.236 grams. Weigh the sand your mass is 41.513 grams, subtract the evaporating dish’s mass from the total mass to get the sand’s mass. The sands mass is 1.277 grams.
Record your data in your lab book.
Safety Issues & Other Suggestions
-Follow standard lab safety protocols in this lab
-You may transport a sample back to AHS and let it dry over the weekend if this would be beneficial
Results: Using the formula for percentage calculations, calculate the percent of the baking soda, and the sand. Total mass/individual items mass X 100 = Percentage.
Individual Total Mass divided by ----------> Individual mass Multiply by 100 Percentage
Sand 13.403 grams 1.277 grams X 100 9.53%
Baking Soda 13.403 grams 6.065 grams X 100 45.25%
Conclusion/Discussion: During this lab we were given a mixture of sand and baking soda, we were asked to find the percentage of each substance in the mixture. After analyzing the data I have concluded that there are possible errors that have occurred that has led to our overall result. Problems such as the following:
• When straining the sand from the vinegar and liquid baking soda some of the sand particles were stuck to the beaker and due to the time we were able to fully get them out of the beaker and on to the plate.
• When we got the mixture of sand and baking soda it was pretty obvious that there was more baking soda in the mixture and less sand.
• When the sand was being heated on the hot plate not all the sand was able to be scraped out of the watch glass.