c) Give the letter of the diagram which shows a mixture Jl Al
element and a compound
In the boxes below, draw the substance indicated.
xygen gas
Carbon dioxide
A mixture of nitrogen
pure substance) A compound
and oxygen
5: Susan makes the following entry in her notebook: "On Friday we were given
a blue liquid in a shallow container. We placed it on the windowsill over the
weekend. On
Monday morning, there was no liquid left, but the dish had some solid blue stuft
in it."
a) Was the blue liquid in the dish a heterogeneous mixture, a solution, or a
pure substance?
b) Explain your answer
Answers
Answer:
Mixtures
If we take two or more pure substances and mix them together, we refer to this as a mixture. Mixtures can always be separated again into component pure substances, because bonding among the atoms of the constituent substances does not occur in a mixture. Whereas a compound may have very different properties from the elements that compose it, in mixtures the substances keep their individual properties. For example sodium is a soft shiny metal and chlorine is a pungent green gas. These two elements can combine to form the compound, sodium chloride (table salt) which is a white, crystalline solid having none of the properties of either sodium or chlorine. If, however, you mixed table salt with ground pepper, you would still be able to see the individual grains of each of them and, if you were patient, you could take tweezers and carefully separate them back into pure salt and pure pepper.
Explanation:
When we speak of a pure substance, we are speaking of something that contains only one kind of matter. This can either be one single element or one single compound, but every sample of this substance that you examine must contain exactly the same thing with a fixed, definite set of properties.