Answer to Question #166006 in General Chemistry for Thao Thanh Le

Question

Materials: 

• 2 - 250 mL beaker     •     Bunsen burner 
• 100 mL beaker     •     Clay triangle 
• 100 mL graduated cylinder     •     Beaker tongs 
• Stirring rod     •     Magnet 

 

Procedure: 

1. Determine the mass of an empty 250 mL beaker and record to the nearest 0.01 grams. 
2. Obtain about 2.0 – 4.0 grams of mixture and determine the mass of the 250 mL beaker plus mixture. 
3. Examine your mixture and record your visual observations about the appearance on your record sheet. 

 

Separating the Iron Filings 

1. Determine the mass of an empty 100 mL beaker and record to the nearest 0.01 gram.   
2. Place the magnet inside a sandwich bag. While holding one end of the magnet, move the other end through the mixture. The iron filings will stick to the magnet. Shake gently to remove any trapped sand. It is not necessary to remove all the iron filings at one time.  
3. Gently lift the magnet with the iron filings and place the end with the filings inside the 100-mL beaker.  Fold the plastic bag over the beaker. Carefully pull the magnet out of the bag, leaving the filings in the beaker.  
4. Repeat steps 5 and 6 to remove the last traces of iron filings from the sand-salt mixture.  
5. Determine the mass of the 100-mL beaker with the iron filings to the nearest 0.01 g.  Record your findings. 

 

Separating the Salt  

1. Heat approximately 100 mL of water in a 250 mL Erlenmeyer flask to about 50-55°C on a hotplate. Add the warm water to the sand-salt mixture.  Stir for at least 2 minutes.  Allow the mixture to settle for at least 1 minute.  
2. Set up a ring stand with an iron ring and clay triangle. Obtain a piece of filter paper and after weighing it on the electronic balance, write the mass in pencil on the paper. Fold the filter paper and place into a funnel as demonstrated by your instructor.  Place the funnel with filter paper into the clay triangle.  Place a preweighed 250-mL “waste” beaker underneath the funnel to collect the salt solution.  Carefully pour the sand/water mixture into the funnel draining into the waste beaker, leaving behind the wet sand in the filter paper.  Allow most of the water to drain through the filter. Place the damp filter paper containing the sand aside. 

 

Recovering the Sand 

1. Place the watch glass containing the wet sand and filter paper on a hot plate set to “medium”.  Heat until the sand appears dry and free-flowing, about 5 minutes.  Remove the watch glass from the hot plate using beaker tongs and let it sit until cool enough to touch. 
2. Determine the mass of the sand to the nearest 0.01 g.  

 

 

Recovering the Salt 

13. Transfer the filtered salt solution to your pre-weighed evaporating dish and place it on the hot plate, now set to high. Heat until the only solid salt remains. When the sample is nearly dry, turn off the hot plate and allow the dish to cool. Obtain the mass of the dish and salt. 

 

 

 

Calculations.  

 

 

The mass percent of a component of a mixture can be calculated as follows:  

 

Mass of Component X

             Mass percent of Component X = 

 

                             Total mass of mixture

Please show your calculations in the spaces provided 

Observations of the mixture       

 

 

 

 

Mass of the 250 mL beaker 

Mass of the 250 mL beaker and mixture 

 

Mass of the mixture 

 

Mass of the 100 mL beaker 

 

Mass of the 100 mL beaker with iron filings 

 

Mass of recovered iron filings 

 

Mass of the filter paper 

 

 

Mass of the filter paper and dried sand 

 

 

Mass of the empty evaporating dish 

 

 

Mass of evaporating dish and salt obtained by evaporation 

 

 

Calculated Mass percent of iron 

 

 

 

 

Calculated Mass percent of sand 

 

 

 

Calculated Mass percent of salt 

 

 

Actual mass percent: 

iron                            sand                             salt 

 

 

 

Percent error iron 

 

 

Percent error sand 

 

 

Percent error salt 

 

Answer 1

250 mL beaker = 77.0g

250 mL beaker + mixture = 80.5g

Mass of mixture = 80.5g - 77.0g

= 3.5g

Mass of the 100 mL beaker = 50.0g

Mass of the 100mL beaker + with iron fillings = 52.8g

Mass of recovered iron filings = 2.80g

mass of filter paper = 0.86g

mass of filter paper + sand = 4.06g,

Mass of the filter paper and dried sand 

 = 3.20g

 

Mass of the empty evaporating dish 

 

 = 21.30g

Mass of evaporating dish and salt obtained by evaporation 

 

 = 21.53g

Calculated Mass percent of iron 

 

 

 = 3.5g/88.50g x 100 %

 

Calculated Mass percent of sand 

 

 = 3.2g/4.06g

 

Calculated Mass percent of salt 

21.53g