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Phosphates

Rock phosphate [Ca 10 (PO 4 ) 6 F 2 ], mined from open pit mines at Phalaborwa, is an important raw material in the production of fertilisers. The following two reactions are used to transform rock phosphate into water soluble phosphates:

  • Ca 10 (PO 4 ) 6 F 2 + 7X + 3H 2 O 3Ca(H 2 PO 4 ) 2 H 2 O + 2HF + 7CaSO 4
  • Ca 10 (PO 4 ) 6 F 2 + 14Y + 10H 2 O 10Ca(H 2 PO 4 ) 2 H 2 O + 2HF
  1. Identify the acids represented by X and Y.
  2. Despite similar molecular formulae, the products Ca(H 2 PO 4 ) 2 formed in the two reactions have different common names. Write down the names for each of these products in reactions A and B.
  3. Refer to the products in reactions A and B and write down TWO advantages of reaction B over reaction A.
  4. Why is rock phosphate unsuitable as fertiliser?
  5. State ONE advantage and ONE disadvantage of phosphate mining.

(DoE Exemplar Paper, Grade 11, 2007)

Case study : controversy on the wild coast - titanium mining

Read the extract below, which has been adapted from an article that appeared in the Mail and Guardian on 4th May 2007, and then answer the questions that follow.

A potentially violent backlash looms in Pondoland over efforts by an Australian company to persuade villagers to back controversial plans to mine an environmentally sensitive strip of the Wild Coast. The mining will take place in the Xolobeni dunes, south of Port Edward. The application has outraged environmental groups, largely because the proposed mining areas form part of the Pondoland centre of endemism, which has more species than the United Kingdom, some of which are endemic and facing extinction.

Exploratory drilling revealed Xolobeni has the world's 10th largest titanium deposit, worth about R11 billion. The amount of money that will be spent over the mine's 22 years, including a smelter, is estimated at R1.4 billion. The Australian mining company predicts that 570 direct jobs will be created.

But at least two communities fiercely oppose the mining plans. Some opponents are former miners who fear Gauteng's mine dumps and compounds will be replicated on the Wild Coast. Others are employees of failed ecotourism ventures, who blame the mining company for their situation. Many are suspicious of outsiders. The villagers have also complained that some of the structures within the mining company are controlled by business leaders with political connections, who are in it for their own gain. Intimidation of people who oppose the mining has also been alleged. Headman Mandoda Ndovela was shot dead after his outspoken criticism of the mining.

Mzamo Dlamini, a youth living in one of the villages that will be affected by the mining, said 10% of the Amadiba 'who were promised riches by the mining company' support mining. 'The rest say if people bring those machines, we will fight.'

  1. Explain what the following words means:
    1. endemic
    2. smelter
    3. ecotourism
  2. What kinds of 'riches' do you think the Amadiba people have been promised by the mining company?
  3. In two columns, list the potential advantages and disadvantages of mining in this area.
  4. Imagine that you were one of the villagers in this area. Write down three questions that you would want the mining company to answer before you made a decision about whether to oppose the mining or not. Share your ideas with the rest of the class.
  5. Imagine that you are an environmentalist. What would your main concerns be about the proposed mining project? Again share your answers with the rest of the class.

Questions & Answers

during a snooker competition ,a 200g ball A m moving with velocity va collide head on with a identical ball B that was at rest.A after the collision ball A remains at rest wile ball B moves on with a velocity of 4m/s? With what speed was ball a moving before the collision
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a vector can be resolved into a horizontal component only
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does a vector quantity include force and distance?
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yes
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vector is the physical quantity with magnitude and direction Scalar is the Physical quantity with magnitude only
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Newton's second law of motion
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Newton second law motin
Shife
Newton's second law of motion: When a resultant/net force acts on an object, the object will accelerate in the direction of the force at an acceleration directly proportional to the force and inversely proportional to the mass of the object.
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down
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states the Newton's second law of motion
Shallin Reply
In words it says:" when a net force is applied to an object of mass, It accelerates in the direction of the net force. The acceleration is directly proportional to the net force and inversely proportional to the mass".
Buhle
And in symbols: Fnet = ma
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hlw
manu
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Mzondi
90°
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manu
fnet=ma
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Madzivha Reply
Hydrogen bonds are the strongest intermolecular forces and London forces are the weakest. Hydrogen bonds exist between polar molecules ( they are a special case of dipole-dipole forces ), while London forces occur between non-polar molecules.
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Andrew Reply
It's when you have equivalent forces going different directions then your resultant will be equal to zero
Temosho
describe what john's experiment proves about water molecules?
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Source:  OpenStax, Siyavula textbooks: grade 11 physical science. OpenStax CNX. Jul 29, 2011 Download for free at http://cnx.org/content/col11241/1.2
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