Answer:
3.98 g
Explanation:
Step 1. Write the balanced chemical reaction. In this case, magnesium reacts with oxygen to produce magnesium oxide:
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Step 2. Calculate the number of moles of magnesium:
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Step 3. Calculate the number of moles of oxygen:
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Step 4. Identify the limiting reactant comparing the equivalents. Equivalent of Mg:
Equivalent of oxygen:
Therefore, Mg is the limiting reactant.
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Step 5. According to the stoichiometry of this reaction:
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Step 6. Convert the number of moles of MgO into mass:
Answer:
<em>2.085 x 10^-20 J</em>
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Explanation:
minimum energy required to produce photoelectric effect in chromium is given as hf = 7.21 x 10^-19 J
The work function of chromium Ф = 4.37 eV = 7.00151 x 10^-19 J
The minimum energy required to eject an electron from from a chromium metal E = ?
From E = hf - Ф
substituting values, we have
E = (7.21 x 10^-19) - (7.00151 x 10^-19)
E = <em>2.085 x 10^-20 J</em>
Answer:
The answer to your question is 2.21 %
Explanation:
Data
mass of Na₂SO₄ = 10.9 g
mass of H₂O = 482 g
Formula
Percent by mass = 
x 100
Substitution
x 100
Simplification and result
x 100
Percent by mass = 0.022 x 100
Percent by mass = 2.21
