Unit 1 Chemistry

extract from the master class teaching materials Our Master Classes form a component of a highly specialised weekly program, which is designed to ensure that students reach their full potential (including the elite A and A+ scores). These classes incorporate the content and teaching philosophies of many of the top schools in Victoria, ensuring students are prepared to a standard that is seldom achieved by only attending school. These classes are guaranteed to motivate students and greatly improve VCE scores! For additional information regarding the Master Classes, please do not hesitate to contact us on (03) 9663 3311 or visit our website at www.tsfx.com.au.

essential for all year 11 and 12 students!

succeeding in the vce, 2017

important notes Our policy at TSFX is to provide students with the most detailed and comprehensive set of notes that will maximise student performance and reduce study time. These materials, therefore, include a wide range of questions and applications, all of which cannot be addressed within the available lecture time. Where applicable, fully worked solutions to the questions in this booklet will be handed to students on the last day of each subject lecture. Although great care is taken to ensure that these materials are mistake free, an error may appear from time to time. If you believe that there is an error in these notes or solutions, please let us know asap (admin@tsfx.com.au). Errors, as well as additional advice, clarifications and important updates, will be posted at www.tsfx.com.au/vce-updates. The views and opinions expressed in this booklet and corresponding lecture are those of the authors/lecturers and do not necessarily reflect the official policy or position of TSFX.

These materials are the copyright property of The School For Excellence and have been produced for the exclusive use of students attending this program. Reproduction of the whole or part of this document constitutes an infringement in copyright and can result in legal action. No part of this publication can be reproduced, copied, scanned, stored in a retrieval system, communicated, transmitted or disseminated, in any form or by any means, without the prior written consent of The School For Excellence (TSFX). The use of recording devices is STRICTLY PROHIBITED. Recording devices interfere with the microphones and send loud, high-pitched sounds throughout the theatre. Furthermore, recording without the lecturers permission is ILLEGAL. Students caught recording will be asked to leave the theatre, and will have all lecture materials confiscated.

it is illegal to use any kind of recording device during this lecture

copyright notice

TSFX - voted number one for excellence and quality in VCE programs.

The School For Excellence 2017 Succeeding in the VCE Unit 1 Chemistry Page 1

QUANTITIES IN CHEMISTRY

SIGNIFICANT FIGURES When performing calculations, you are required to state answers to the appropriate number of significant figures. A significant figure indicates the precision to which a value or measurement is given. A significant figure is: A non-zero digit. A zero that follows a digit. Therefore:

All non-zero digits are significant. For example: 1, 2, 3, 23, 341 Zeros which follow a non-zero digit are significant. For example: 200, 0.0001500 Zeros which come before a non-zero digit are insignificant. For example: 0.0001500 Any zero between two digits is significant. For example: 20.00046 How many significant figures? Count the number of figures from the first non-zero digit. Examples: 38.4 has 3 significant figures. 20.03 has 4 significant figures. 500 has 3 significant figures. 0.007 has 1 significant figure. 0.00700 has 3 significant figures.

The School For Excellence 2017 Succeeding in the VCE Unit 1 Chemistry Page 2

MATHEMATICAL OPERATIONS

Addition and Subtraction When adding or subtracting numbers, count the number of decimal places to determine how many significant figures should appear in the answer. The answer cannot contain more decimal places than the smallest number of decimal places in the numbers being added or subtracted. For example: The sum of the numbers 0.25, 1.3324, 23.112233 is: 23.112233 6 decimal places 8 significant figures 1.3324 4 decimal places 5 significant figures 1.25 2 decimal places 3 significant figures The sum of these numbers (25.694633) must be written to the same number of decimal places as the value with the smallest number of decimal places i.e. 1.25 Therefore, the answer is 25.69, which has 4 significant figures.

Multiplication and Division When multiplying or dividing numbers, the answer must be written to the same number of significant figures as the piece of data with the smallest number of significant figures. For example: 39.100 3 decimal places 5 significant figures 1.0 1 decimal place 2 significant figures 12.00 2 decimal places 4 significant figures 48.0 1 decimal place 3 significant figures The sum of these numbers must be written correct to 1 decimal place i.e. 100.1 (which has 4 significant figures!) The product of these numbers (8445.6) must be written to 2 significant figures i.e. . Note: Do NOT consider counting numbers in significant figures.

Significant figures are only considered in the FINAL answer.

Do not round off values until the final step (i.e. round when stating the final answer).

38.4 10

The School For Excellence 2017 Succeeding in the VCE Unit 1 Chemistry Page 3

STANDARD FORM A value written in standard form lies between 1 and 10, and is multiplied by a power of 10. For example: 0.102 is written as 11.02 10

102 is written as 21.02 10

0.000102 is written as 41.02 10

400 is written as 24.00 10 Standard form is used to express a large or very small number value to a small number of significant figures. For example: 371.74 becomes 2107.3 , correct to 2 significant figures. Note: If you are able to eliminate zeros by writing a number in scientific notation, then these zeros are not significant. For example: 0.00040 can be written as , and hence has 2 significant figures.

QUESTION 1 Consider the following numbers: 107.9, 16.42, 7.02, 8.30, 9.1 (a) The least number of significant figures in this data is __________________.

(b) If these figures were added the answer would be: __________________.

(c) The product of these numbers is: __________________.

44.0 10

The School For Excellence 2017 Succeeding in the VCE Unit 1 Chemistry Page 4

RELATIONSHIPS USED IN STOICHIOMETRY

Stoichiometry involves the calculation of the amounts of chemical substances.

THE MOLE The mole is defined as the amount of substance contains the same number of formula units as there are atoms in 12 grams of the carbon-12 isotope i.e. 23100226.6 formula units. This quantity is known as Avogadro's Constant ( AN ).

1 mole of a substance contains 23100226.6 formula

units of that substance The symbol for the amount of substance (mole) is n and the unit of measurement is mol .

RATIOS IN CHEMICAL FORMULAE In order to solve quantity based questions in chemistry, we may need to use ratios in chemical formulae. As an example, a molecule of water, 2H O , is made up of 2 atoms of hydrogen and 1 atom of oxygen. We say that these atoms have combined in a 2 to 1 ratio (2 : 1). We can use these ratios to determine the amount of any chemical species in any given scenario. For example: 100 molecules of water are made up of 200 atoms of hydrogen and 100 atoms of

oxygen.

2 mole of water is made up of 4 mole of hydrogen atoms and 2 mole of oxygen atoms. Note: Ratios cannot be used directly to determine the mass of each element in a compound. For example: 1 gram of 42SOH does not contain 2 grams of

H , 1 gram of S atoms and 4 grams of O atoms.

The School For Excellence 2017 Succeeding in the VCE Unit 1 Chemistry Page 5

QUESTION 2 In one mol of aluminium hydroxide, Al(OH)3.3H2O, there are: A 3 mol of aluminium atoms. B 5 mol of hydrogen atoms. C 16 mol of atoms. D 4 mol of oxygen atoms.

CALCULATIONS INVOLVING AVOGADROS CONSTANT

( ) ANumber of Particles n particles N Step 1: Calculate the amount, in mol, of the given substance. Step 2: Use mole ratios to determine the amount, in mol, of the particle being counted. For example: 1 mole of 42 SOH contains

2310023.6 42 SOH molecules. 1 mole of 42 SOH contains 2 2310023.6 atoms of hydrogen. 1 mole of 42SOH contains 3

2310023.6 ions (when in an aqueous solution). Step 3: Multiply the amount, in mol, by Avogadro's Constant.

Number of Particles (N)

Amount of Substance (n)

NA

NA

The School For Excellence 2017 Succeeding in the VCE Unit 1 Chemistry Page 6

QUESTION 3 How many particles of 4CuSO are present in 2.00 mole 4CuSO ? Solution

( ) ANumber of Particles n particles N

2423 1021.1110023.600.2 AN particles

QUESTION 4 Given 3.0 mol of ethanol, 2 5C H OH , calculate: (a) The number of mol of carbon atoms. (b) The number of mol of hydrogen atoms. (c) The number of mol of oxygen atoms. (d) The number of carbon atoms. (e) The number of hydrogen atoms. (f) The number of oxygen atoms. (g) The number of atoms.

The School For Excellence 2017 Succeeding in the VCE Unit 1 Chemistry Page 7