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Assessment and grading criteria Essay

Unit 1 – Fundamentals of Science
Assessment and grading criteria
To achieve a pass grade the evidence must show that the learner is able to: To achieve a merit grade the evidence must show that, in addition to the pass criteria, the learner is able to: To achieve a distinction grade the evidence must show that, in addition to the pass and merit criteria, the learner is able to: P1

outline the key features of the periodic table, atomic structure and chemical bonding M1brelate the key features of the periodic table to the conclusions drawn from the practical activities D1vexplain how standard solutions and titrations are prepared in industry P2vdemonstrate practically the ability to prepare chemical solutions and test their accuracy

Scenario:
You are working as a scientist for ‘Edvisprog’ – a company producing visual aids for education. The team is currently working on a web-based program to help students understand the key features of the periodic table and information to guide students to help the teaching and understanding of the use of titrations. You have to produce word documents or powerpoint presentations that will provide the information for the web-based software.

Remember:
During this (and other assignments) credit cannot be given for a diagram copied from the internet unless, (1) It is referenced and (2) You have interpreted the diagram in some way, for example, added your own labels or further described the concept conveyed in the diagram. Task 1 – Chemical Bonding and the Periodic Table

In this task you have to describe atomic structure, outline the key features of the periodic table and describe chemical bonding

Draw a diagram of a Calcium atom, label the key components of the atom. P1i

The periodic table contains over 100 different elements in a specific order. Describe how the atoms in the periodic table are arranged. You will need to make reference to (a) groups, (b) periods, (c) metals and non-metals, (d) solids/liquids/gases. Choose three different elements and explain why each is in a particular group / period P1ii

Ionic, covalent and hydrogen are the three main types of chemical bonding. Draw a series of diagrams, with explanations to outline the process involved in each type. P1iii

Task 2 – Volumetric Analysis
This task will require you to make a ‘Standard Solution’, this is a solution of known strength. You will make a solution of sodium carbonate. The strength of sodium carbonate (Na2CO3) is usually measured in moles. A one molar (1M) solution means one mole of substance (solute) per litre of solution. A mole is the molecular mass of a substance in grams.

To calculate the molecular mass, the atomic masses of all the atoms in the molecule need to be added together. For example, the sodium carbonate molecule consists of one atom each of sodium (Na), carbon (C), and oxygen (O). Their respective atomic weights are: Na – 23,C – 12 and O – 16, so the molecular weight, is 23 + 23+ 12 + 16 + 16 + 16 = 106. Thus 106 grams of Na2CO3 equals one mole of Na2CO3, and a 1 molar solution of Na2CO3will contain 106 grams of Na2CO3chemical, per litre of water.

Using all the safety measures required, make a ‘Standard Solution’ of sodium
carbonate. It can be any strength you like (within reason!) but you must know the strength exactly.

This part of the task will be assessed by the teacher.
P2i

You will now use your standard solution to calculate the strength of a sample of HCl (Hydrochloric Acid).

Procedure…
1. Rinse all equipment with distilled water
2. Using a pipette add 25 cm3 of Na2CO3 to a conical flask
3. Add 3 or 4 drops of phenolphthalein. The solution will turn pink. 4. Fill the burette with Hydrochloric acid.
5. Add acid to the alkali, note how much acid is needed to neutralise the sodium carbonate, the solution will turn clear (to the nearest 1cm3) 6. Repeat the experiment a further three times, this time being accurate to 0.1 cm3 7. Take the average of the acid needed (from the three experiments in the previous step).

P2ii
Calculate the strength of the acid using the following information…

Na2CO3 + HCl  NaHCO3 + NaCl
At equilibrium: Moles of Na2CO3 = Moles of HCl (as they react in a 1:1 ratio)

Molarity of HCl (moles per litre) x Volume of HCl (litres) = Molarity of Na2CO3 (moles per litre) x Volume of Na2CO3 (litres)

Molarity of HCl (moles per litre) = Molarity of Na2CO3 (moles per litre) x Volume of Na2CO3 (litres or ml)
Volume of HCl (litres or ml)
P2iii
M1i

Task 3 – Further Calculations

This task requires you to further understand and describe the molecular changes from the previous experiment. The experiment reacted Na2CO3 with HCl to make NaCl and H2O. 1. Explain what makes HCl an acid/

2. Explain what makes Na2CO3 an alkali, when dissolved in water? The diagram of Sodium carbonate may help you to explain this

3. Why does the hydrogen (H) form a positive ion in a hydrochloric acid solution? 4. When acids and alkalis react they form a salt, explain why a salt (in this case NaCl) is a very stable compound? 5. Explain why Sodium is in group 1, period 3 and Chlorine is in group 7, period 3. M1ii

Explain in detail how you prepared your base solution, including the calculations. D1i

Task 4 – Titrations in Industry
Standard solutions are used in the chemical industry to measure and check the strength of chemicals. One particular example is the conversion of WVO (waste vegetable oil) into biofuel for diesel engines. The pH of WVO needs to be altered so it is approximately 8.5, which is the same as normal diesel.

Explain how the pH of WVO is measured in an industrial setting and why the pH must be accurately determined. The following websites may be useful:
http://en.wikipedia.org/wiki/Titration
http://alternativefuels.about.com/od/biodiesel/a/bdtitration.htm D1ii
Edexcel Level 3 BTEC Nationals in Applied Science (Forensic Science)Name…………………………. Unit 01 – Fundamentals of Science
Assignment 01-01, Volumetric Analysis

Unit 1 – Fundamentals of Science
Assessment and grading criteria To achieve a pass grade the evidence must show that the learner is able to: To achieve a merit grade the evidence must show that, in addition to the pass criteria, the learner is able to: To achieve a distinction grade the evidence must show that, in addition to the pass and merit criteria, the learner is able to: P1

outline the key features of the periodic table, atomic structure and chemical bonding M1 relate the key features of the periodic table to the conclusions drawn from the practical activities D1 explain how standard solutions and titrations are prepared in industry P2 demonstrate practically the ability to prepare chemical solutions and test their accuracy

Marking Grid:
Task 1 – Chemical Bonding and the Periodic Table
P1i
Labelled diagram of atom
Yes / No

P1ii
Key features of periodic table
Yes / No

P1iii
Key features of chemical bonding
Yes / No
Feedback:

Task 2 – Volumetric Analysis
P2i
Experiment conducted safely
Yes / No

P2ii
Basic results from experiment obtained
Yes / No

P2iii/M1i
Molarity of HCl calculated
Yes / No
Feedback:

Task 3 – Further Calculations
M1ii
Questions answered about acids, bases and the periodic table Yes / No

D1i
Explained how standard solution was made, including calculations Yes / No
Feedback:

Task 4 – Titrations in Industry
D1ii
Describe the titration of WVO and the subsequent implications Yes / No
Feedback:

Criteria Awarded:
P1
P2
M1
D1
Date:

Student Response to Feedback:Date:

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