# Chemistry

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1. Stoichiometry
(sometimes called reaction stoichiometry to distinguish it from composition stoichiometry) is the calculation of quantitive relationships of the reactants and products in a balance chemical reaction. It can be used to calculate quantities such as the amount of products that can be produced with the given reactants and percent yield.
2. Intensive property
A property- such as temperature, melting point, and density- that does not depend on the amount of the sample being examined.
3. Extensive Property
A property of a substance that depends on the quantity of the sample.
4. Precision
Is a measure of how closely individual measurements agree with one another.
5. Accuracy
How closely individual measurements agree with the correct, or "true," value.
6. Significant Figures
• All digits of a measure quantity, including the uncertain one.
• Ex: 4.0 g has two significant figures. 4.00 g has 3 significant figures.
• The greater the number of significant figures, the greater is the certainty implied for the measurement.
• 1. Zeros between nonzero digits are always significant- 1005 kg (four significant figures); 1.03 (three significant figures)
• 2.Zeros at the beginning of a number are never significant- 0.02g (one significant figure); 0.0200g ( three significant figures)
• 3. Zeros at the end of a number are significant if the number contains a decimal point- 0.0200g (three significant figures); 3.0 cm (two significant figures)
• other examples: 1.03 x 10^4 g (three significant figures; 1.030 x 10^4 g (four significant figures)
• When carrying measured quantities through calculations, the least certain measurement limits the certainty of the calculated quantity and thereby determines the number of significant figures in the final answer.
7. Dimensional Analysis
• Carrying all units throughout the calculation to make sure we get the right unit in the end.
• Given unit x desired unit/ given unit = desired unit
8. Cathode rays
• Streams of electrons that are produced when a high voltage is applied to electrodes in an evacuated tube.
• Experiments with this, help led the discovery of electrons.
9. Aqueous solutions
Solutions in which water is the dissolving medium
10. Solution
A homogenous mixture of two or more substances.
11. Electrolye
A substance (such as NaCl) whose aqueous solutions contain ions.
12. Nonelectrolyte
A substance (such as C(12)H(22)O(11)- sucrose) that does not form ions in a solution.
13. Solvation
The process where as an ionic compound dissolves, the ions become surrounded by H(2)O molecules.
14. Strong electrolytes
are those solutes that exist in a solution completely or nearly complete as ions.
15. Weak electrolytes
are those solutes that exist in solution mostly in the from of molecules with only a small fraction in the form of ions.
16. Precipitation reactions
Reactions that result in the formation of an insoluble product
17. Precipitate
An insoluble solid formed by a reaction in a solution.
 Author: opher ID: 197763 Card Set: Chemistry Updated: 2013-02-12 03:48:04 Tags: Chemistry Folders: Description: Chemistry Show Answers: