Answer:
The wavelength the student should use is 700 nm.
Explanation:
Attached below you can find the diagram I found for this question elsewhere.
Because the idea is to minimize the interference of the Co⁺²(aq) species, we should <u>choose a wavelength in which its absorbance is minimum</u>.
At 400 nm Co⁺²(aq) shows no absorbance, however neither does Cu⁺²(aq). While at 700 nm Co⁺²(aq) shows no absorbance and Cu⁺²(aq) does.
Answer:
10.52g KOH
Explanation:
250.0 ml X 1L/1000ml X 0.75 mol KOH/1L X 56.105gKOH/1 mol KOH =10.52g KOH
Answer; chemical reaction
<span>These are five questions with its five answers.
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</span><span>First, we have to explain main question.
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</span><span>The statement provides the chemical equation for the reaction of Fe with water to produce iron(III) oxide and hydrogen.
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</span><span>Fe3O4 is a weird chemical formula. It belongs to the product named oxoiron.
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Next, I have to tell how you must interpret the question. The five questions are based on the complete reaction of the same number of moles as the coefficients indicated in the chemical equation.
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<span>Those coefficients are 3 for Fe, 4 for H₂O, 1 for Fe₃O₄ and 4 for H₂.
With that understood, let's work every question.
1) How many molecules of H₂ are produced?
Answer: 4 moles of molecules.
</span><span>Justification:
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<span /><span /><span>This is, the number of moles of H₂ produced is given by the coefficient indicated in the chemical equation.
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<span>2) How many oxygen atoms are required?
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<span>Answer: 4.
</span><span>This is, the atoms of oxygen are supplied in the molecules of water. Since the coeffcient of water is 4, and each molecule o fwater has 1 atom of oxygen, 4 moles of water contain 4 moles of atoms of oxygen.
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3) How many moles of Fe₃O₄ are formed?
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<span>Answer: 1.
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<span>Justification: the coefficient of for formula Fe₃O₄ is 1, indicating that the theoretical yield is 1 mol of molecules.
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<span>4) What is the mole ratio of Fe to H₂O?
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<span>Answer: 3:4
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<span>Justification:
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</span><span>The ratio is the quotient of the two coefficients: the coefficient of the Fe divided by the coefficient of the H₂O.
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5) How many hydrogen atoms are involved in this reaction?
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<span>Answer: 8 moles of hydrogen atoms.
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<span>Justification: as you can see each molecule of H₂O has 2 atoms of hydrogen, then 4 moles of molecules of H₂O have 8 moles of atoms of hydrogen. And of course the same number are in the produt: 4 moles of H₂ contain 8 moles of atomos of hydrogen
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This is a difficult task because zinc is much more active than copper and could hardly be passivated. ... The sur- face immediately turns white (the color of copper(I) iodide) and the yellow-brown color of iodine quickly fades. Rinse the coin with water, brighten it with polish and cloth and begin the whole process again.N
