10. A student did an experiment to calculate percent composition of a mixture of
ID: 696933 • Letter: 1
Question
10. A student did an experiment to calculate percent composition of a mixture of sand and Potassium chloride. At the end of the experiment, student determined that the mixture had 29 percent of sand and 29 percent of potassium chloride. Do you then this data make sense? Explain your reasoning 11. Phenolphthalein is not a good indicator to test Hydrochloric acid. True or false? Explain your reasoning. 12. To test the strength of an acid or base, we can either use ph paper or ph meter. Which one of these two tests is less accurate? Explain your reasoning by giving specific example. 13. Give two examples of heterogeneous mixtures in the following system Solid-solid : Example Solid-liquid 14. Give two examples of homogeneous mixtures in the following system Gas- Gas Liquid-liquid: Example A chemist heated an unknown hydrate, MgSO. X HO, in a crucible with a mass of 2 gr. The water was driven off three times, leaving the anhydrous salt in the crucible. After final cooling, the mass of the water lost was 0.05 and the mass of the hydrate more than three times? Please explain. 15. anhydrous salt was 1.5. Do you think it was necessary to heat theExplanation / Answer
10. It is wrong.
Because he mixture of has only tow components. So, total percentage of two components must be equal to 100. But it is given that 29 + 29 = 58 which makes incorrect.
11. No. It is not good choice.
Because it changes color after the equivalence point is just passed if we add HCl to weak base. If we add weak base to HCL it gives color change befor equivalence poit is reached.
12.
pH meter is best choice because to gives accurate values.
13.
Solid - Solid = iron and sand
Solid - liquid = sand and water
14.
Liquid - liquid = water + ethyl alcohol
Gas - gas = O2 gas + N2 gas
15.
mass of hydrated salt = 2 g.
Mass of water lost = 0.05 g.
Mass of the anhydrous salt = 1.5
Total mass = 1.5 + 0.05 = 1.55 g.
But we have 2 g. of anhydrous salt. Hence it is necessary to heat salt to give off more amount of water which is still remained there.
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