Chem 161-2009 homework 1st & 2nd week combined

Chem 161-2009 homework 1st & 2nd week combined -...

Info iconThis preview shows pages 1–3. Sign up to view the full content.

View Full Document Right Arrow Icon
ST ND WEEK COMBINED Chapter 1 homework: 7. How do physical and chemical properties differ? With a physical property, such as boiling point, the molecule doesn’t change; e.g., when water boils it goes from a liquid to a vapor, but the H 2 O molecule remains as H 2 O. A chemical property, such as oxidation, results in a change in the molecule. Hence, H 2 O + O 2 → H 2 O 2 , a different molecule than H 2 O. 11. An example of a homogeneous mixture or solution is A mixture or a solution must contain at least two substances. (a) maple syrup This is a homogeneous mixture. It is homogeneous because it exists in only one phase. It is a mixture because it contains many substances, e.g., sugar, water, flavoring. (b) liquid oxygen Oxygen is a pure substance. It is not a mixture or a solution because it only contains a single substance. (c) distilled water Water is a pure substance. It is not a mixture or a solution because it only contains a single substance. (d) chicken soup This is not homogeneous since it exists as more than one phase (a solid phase – noodles, and a liquid phase – water). It is a heterogeneous mixture. 23. Which of the following are examples of matter? (a) iron Matter is something that has mass. Iron has mass. (b) the human body Matter is something that has mass. The human body has mass. (c) blue light Matter is something that has mass. Blue light doesn’t have mass. It is energy. (d) a meteor Matter is something that has mass. A meteor has mass. (e) the balance in a checking account Matter is something that has mass. The balance in a checking account has no mass. 27. Which of the following are substances and which are mixtures? Explain. (a) helium gas used to fill a balloon A substance is an individual compound or element. Helium is an element. Therefore it’s a substance. (b) the juice squeezed from a lemon Juice is a mixture of substances, and therefore a mixture. It contains acetic acid, fructose, water, etc. (c) a premium red wine Wine is a mixture of substances, and therefore a mixture. It contains flavoring molecules, water, fructose, etc. (d) salt used to de-ice roads The answer depends on whether the salt is pure or impure NaCl. I would guess that salt used to de-ice roads is not pure, so it is therefore a mixture. 31. Can a set of measurements be precise without being accurate? Yes. For example, if the analytical balance is not calibrated correctly, one might get very reproducible answers, but the average might not be 1
Background image of page 1

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
the correct answer. Can the average of a set of measurements be accurate even if the individual measurements are imprecise? Yes. The answers can vary considerably, but if the average answer is the correct one then by definition the average is accurate, but not precise. Explain. 35.
Background image of page 2
Image of page 3
This is the end of the preview. Sign up to access the rest of the document.

This document was uploaded on 11/02/2011 for the course GEN CHEM 162 at Rutgers.

Page1 / 10

Chem 161-2009 homework 1st & 2nd week combined -...

This preview shows document pages 1 - 3. Sign up to view the full document.

View Full Document Right Arrow Icon
Ask a homework question - tutors are online