1- Identify the following changes as chemical or physical: A-The steak dinner yo

Question

1- Identify the following changes as chemical or physical:

A-The steak dinner you ate is being digested and used for energy,

B-Iron rusts when left in a moist environment,

C-Dry ice (solid carbon dioxide) sublimes to form carbon dioxide gas,

D- A student drops a 50mL beaker that breaks into 17 pieces,

e- A battery terminal corrodes when battery acid is spilled on the terminal.

2. During filtration, the recommended procedure is to wash the solid three times. Beriefly explain why three washings are needed.

3- Why should you use a cool flame when you are heating the solution after filtration ?

4- The mass of an aluminum boat is 4.9682 g. The mass of an aluminum boat and mixture of boat and a mixture of and, NaCl, and (NH4)2CO3 is 6.5172 g.After sablimation of (NH4)2CO3, the mass of the boat and mixture is 6.1532 g. Water is added to the mixture and the resulting solution is filtered. After rhe sand is dried, the mass of the sand is 0.7648 g. After evaporation of the filtrate , the mass of salt is 0.4024 g. Calculate the % of sand, % of NaCl, and the % of (NH4)2CO3 in the mixture (show all calculations). Do these precentages add to 100%? if not, provide an explanation.

Explanation / Answer

1. A. physical

B. chemical

C. physical

D. physical

E. chemical

3. Because of the thickness of the glass. Glass that is thin, as in test tubes expand with heat rather quickly and this makes them very fragile

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