The element oxidized in the reaction described in PbO2 + 4HCl → 2H2O + PbCl2 + Cl2 is A. Pb. B. O. C. H. D. Cl.
Answers
An element or compound's oxidation number is mainly dependent on its charge, except in special cases.
In PbO₂, Oxygen's oxidation number is always -2, except in hydrogen peroxide where it is -1. Since PbO₂ is neutral, its total oxidation number must be 0. Since there are two oxygens with an oxidation number of -2, we know that Pb's oxidation number is +4, since +4 -2×2 = 0.
Using the same method we can find Pb's oxidation number in PbCl₂. Unless paired with another halogen, which it isn't, Cl in a compound has an oxidation number of -1, so Pb = +2 since +2 -1×2 = 0.
Pb's oxidation number has gone from +4 to +2, so it has been reduced, so A. Pb is not the answer.
Oxygen in a compound's oxidation number is always -2 unless in H₂O₂ and it isn't on either side of the equation, so its oxidation number doesn't change and it remains in a compound, so B. O is not the answer.
Hydrogen in a compound's oxidation number is always +1, except in hydrides when it is -1, but it isn't, so it doesn't change , so C. H is the answer.
Therefore D. Cl is correct, since its oxidation number increases from -1 in HCl to 0 in Cl2 (since elements not in a compound have an oxidation number of 0)
Hope this helps!
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17 g/mole / (0.68)^2 = 36.8 g/mole
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Answer:
33.21% is the right answer.
Explanation:
0.04720 L * 0.02240 mol / L = 1.0573*10-3
mol Fe+2 = 1.0573* 10-3 mol = 5.2864*10-3
mass of Fe= 5.2864 * 10-3 = 0.29522g
% of Fe in sample = 0.29522 g Fe / 0.8890 g of sample * 100 = 33.21%
Final answer:
The number of moles of MnO4– added to the solution is 0.00106 mol. The moles of Fe2+ in the sample is 0.00530 mol. The grams of iron in the sample is 0.296 g and the percentage of iron in the sample is 33.33%.
Explanation:
The titration reaction between Fe2+ and MnO4– in acid solution is as follows: 5Fe2+ + MnO4– + 8H+ → 5Fe3+ + Mn2+ + 4H2O. Firstly, we can calculate the number of moles of MnO4– added to the solution using the formula volume X molarity. That is 0.0472 L X 0.02240 M = 0.00106 mol MnO4–. According to the balanced redox reaction, one mole of MnO4– reacts with five moles of Fe2+. Therefore, the moles of Fe2+ in the sample is 0.00106 mol MnO4– X 5 = 0.00530 mol Fe2+.
Next, we calculate the grams of iron in the sample. The molarmass of iron is approximately 55.85 g/mol, thus the grams of iron in the sample are 0.00530 mol Fe2+ X 55.85 g/mol = 0.296 g Fe2+. Finally, we find the percentage of iron in the sample by mass = (mass of iron in the sample / total mass of the sample) X 100%. Therefore, the percentage is (0.296 g / 0.8890 g) X 100% = 33.33%.
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Molality can be expressed by moles of solute over kilograms of solvent. The question asks the molality of 0.25m NaCl. 0.25m NaCl is equal to 0.25 moles of NaCl over 1 kg of water.
0.25 moles of NaCl over 1 kg of water
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Answer: In the following equation, is considered as a binary compound.
Explanation: A binary compound is considered as a compound having 2 elements only. In the following chemical equation:
There are 2 compounds present because compound is defined as the chemical combination of two or more elements in a fixed ratio.
In the equation, compounds are: and
consists of 2 elements which are hydrogen and oxygen and hence is considered as a binary compound.
consists of 3 elements which are sodium, hydrogen and oxygen and hence, cannot be considered as a binary compound.
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Final answer:
Water helps in maintaining temperature in cells due to its high heat capacity. This property allows water to absorb or release a large amount of heat without significantly changing its own temperature. As such, cells can keep a stable temperature despite environmental changes.
Explanation:
Water has a high heat capacity, which is the amount of heat it takes to change its temperature. Due to this high heat capacity, it can absorb or release a large amount of heat without a significant change in its own temperature. This helps cells maintain a relatively stable temperature and protect biological processes. For instance, when the external environment is hot, cells can avoid getting overheated as the water in them absorbs and distributes the heat evenly. Similarly, if the environment is cold, the water in the cells releases heat which helps to keep them warm. Hence, regardless of the temperature changes in the environment, the high heat capacity of water aids cells in preserving a relatively even temperature.
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