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C8: Quiz 1 – Answers
C8: Quiz 1 – Answers
1) A substance is pure if it is made up of a single element or a single compound
2) at a single temperature, over a range of temperatures
Pure substances melt/ boil at a single temperature. Impure substances melt/ boil over a range of temperatures.
3) Lower, higher
The melting point of an impure substance will be lower than the melting point of the pure substance.
The boiling point of an impure substance will be higher than the boiling point for the pure substance.
4) Substance B is the most impure as it melted over a range of temperatures (76-79°C), whereas substance A melted at a single temperature. Also, substance B had the lower melting point and we know that as the impurity increases, the melting point becomes lower
5) Solution B has a boiling point (101.2°C) that is further away from the known boiling point of water (100°C), which means that solution B is more impure. Therefore, solution B will have a greater concentration of salt.
6)
a) Anything like the definition below.
Formulations are mixtures that have been designed as useful products. Many products are complex mixtures in which each of the chemicals in the mixture has a particular purpose. We make formulations by mixing the different substances in specific quantities to ensure that the products have the required properties.
b) Any two from fuels, cleaning agents, paints, medicines, alloys, foods etc.
2) at a single temperature, over a range of temperatures
Pure substances melt/ boil at a single temperature. Impure substances melt/ boil over a range of temperatures.
3) Lower, higher
The melting point of an impure substance will be lower than the melting point of the pure substance.
The boiling point of an impure substance will be higher than the boiling point for the pure substance.
4) Substance B is the most impure as it melted over a range of temperatures (76-79°C), whereas substance A melted at a single temperature. Also, substance B had the lower melting point and we know that as the impurity increases, the melting point becomes lower
5) Solution B has a boiling point (101.2°C) that is further away from the known boiling point of water (100°C), which means that solution B is more impure. Therefore, solution B will have a greater concentration of salt.
6)
a) Anything like the definition below.
Formulations are mixtures that have been designed as useful products. Many products are complex mixtures in which each of the chemicals in the mixture has a particular purpose. We make formulations by mixing the different substances in specific quantities to ensure that the products have the required properties.
b) Any two from fuels, cleaning agents, paints, medicines, alloys, foods etc.
Questions
1) What is the definition of a pure substance?
2) Fill in the gaps in the sentence below with the phrases “over a range of temperatures” and “at a single temperature”
Pure substances melt/ boil ___________. Impure substances melt/ boil ___________.
3) Fill in the gaps in the paragraph below with the words “higher” and “lower”
The melting point of an impure substance will be _______ than the melting point of the pure substance.
The boiling point of an impure substance will be _______ than the boiling point for the pure substance.
4) We have 2 samples of a substance with different impurities; substance A and substance B. Substance A melts at 80°C and substance B melts at temperatures between 76-79°C. Which substance is the most impure? Explain your answer.
5) Pure water boils at 100°C.
We have 2 solutions of saltwater; solution A and solution B. We heat both of these solutions to find their boiling points. Solution A has a boiling point of 100.9°C and solution B has a boiling point of 101.2°C.
Suggest which substance has a greater concentration of salt. Explain your answer.
6)
a) What is a formulation?
b) Give two examples of formulations.
1) What is the definition of a pure substance?
2) Fill in the gaps in the sentence below with the phrases “over a range of temperatures” and “at a single temperature”
Pure substances melt/ boil ___________. Impure substances melt/ boil ___________.
3) Fill in the gaps in the paragraph below with the words “higher” and “lower”
The melting point of an impure substance will be _______ than the melting point of the pure substance.
The boiling point of an impure substance will be _______ than the boiling point for the pure substance.
4) We have 2 samples of a substance with different impurities; substance A and substance B. Substance A melts at 80°C and substance B melts at temperatures between 76-79°C. Which substance is the most impure? Explain your answer.
5) Pure water boils at 100°C.
We have 2 solutions of saltwater; solution A and solution B. We heat both of these solutions to find their boiling points. Solution A has a boiling point of 100.9°C and solution B has a boiling point of 101.2°C.
Suggest which substance has a greater concentration of salt. Explain your answer.
6)
a) What is a formulation?
b) Give two examples of formulations.