When calculating total valence electrons, extra electron pairs are added to the Outside of an atom. The answer is letter C. Suppose you have a compound of CCl4. You know that chlorine can only share 1 electron because 7 of its electrons are filled. Also, in carbon, it can only share 4 electrons because 4 of it are already filled. That is why carbon needs four chlorine to form CCl4.
a. True
b. False
1. Which of the following items represents a chemical change? burning melting evaporation freezing
Answer:
Explanation:
Chemical properties depend on composition while physical properties do not depend on composition. As in case of burning, composition changes due to this , this is chemical properties while freezing, melting and evaporating process, composition remain same, so these have physical properties, like water in liquid, ice and vapor state have same composition.
2. The physical properties of a compound are similar to those of its elements.
Answer:
Explanation:
In the context of Chemistry, 'Burning' is a chemical change as it results in new substances. The claim that a compound's physical properties are similar to its elements is typically false as the properties often differ significantly, an example being the difference between water and its constituent elements hydrogen and oxygen.
The question falls under the field of Chemistry. It refers to the concept of chemical and physical changes in matter. A chemical change is a change in matter that results in the formation of one or more new substances with new properties. On the contrary, a physical change relates to a change in the state of matter without any change in its chemical composition. Out of the options given, the process of 'Burning' symbolizes a chemical change as it results in the formation of new substances such as carbon dioxide, water vapor, etc.
As for the second part of your question, the statement that 'physical properties of a compound are similar to those of its elements' is generally false. The properties of a compound often differ greatly from those of the constituent elements. One classic example is that of water (H2O). Water is a liquid at room temperature, quenches thirst, and is essential for life. However, its constituent elements - Hydrogen and Oxygen - are both gases and do not possess these characteristics.
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Answer:
Mn: 3+
Cl: 7+
O: 2-
Explanation:
1) Compound given: Mn [ClO₄]₃
2) Initially you only know the oxidation state of O, since it is always 2-, except when it form peroxides, which is not the case.
3) So, you do not know the oxidation states neither of the Mn nor of the Cl, and you need some more information.
You might start from the ion [ClO₄] but you do not know its charge.
This ion comes from one of the oxoacids formed by Cl. Those are four different acids. These are them:
i) Oxidation state 1+: Cl₂O + H₂O → H₂Cl₂O₂ = HClO ⇒ ion ClO⁻
ii) Oxidation state 3+: Cl₂O₃ + H₂O → H₂Cl₂O₄ = HClO₂ ⇒ ion ClO₂⁻
iii) Oxidation state 5+: Cl₂O5 + H₂O → H₂Cl₂O₆ = HClO₃ ⇒ ion ClO₃⁻
iv) Oxidation state 7+: Cl₂O₇ + H₂O → H₂Cl₂O₈ = HClO₄ ⇒ ion ClO₄⁻
Finally, we have that our ion is ClO₄⁻ and the oxidation state of Cl is 7+.
4) Now you just have to find the oxidation state of Mn, for which you make a balance of charges:
Mn [ClO₄]₃
Since, the ion ClO₄⁻ has 1 negative charge, and there are 3 ions the total negative charge is 3-. Since the compound is neutral, you conclude that Mn has oxidation state 3+.
That according to this balance: 1(3+) + 3(1-) + 3 - 3 = 0.
5) Summarizing, the oxidation states are:
Mn: 3+
Cl: 7+
O: 2-
Percent solution of NaCl = 3.26%
Step 1: Determine the mass of NaCl in the initial solution
The initial solution is 25% NaCl, which means there are 25 grams of NaCl for every 100 grams of solution. To find the mass of NaCl in the 75g solution, use this proportion:
(25g NaCl / 100g solution) = (x / 75g solution)
Solve for x:
x = (25g NaCl * 75g solution) / 100g solution
x = 18.75g NaCl
Step 2: Determine the total mass of the diluted solution
Add the mass of water (500g) to the mass of the initial solution (75g):
Total mass = 500g water + 75g solution = 575g diluted solution
Step 3: Calculate the percentage of NaCl in the diluted solution
Use the mass of NaCl from Step 1 and the total mass of the diluted solution from Step 2 to find the percentage by mass:
Percentage = (Mass of NaCl / Total mass of diluted solution) * 100
Percentage = (18.75g NaCl / 575g diluted solution) * 100
Percentage ≈ 3.26%
The percent solution by mass of NaCl in the diluted solution is approximately 3.26%.
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