Balance equation: Ca(s) + O2(g) -> CaO(s) What is the coefficient for CaO in this reaction? A2 Consider the following particulate-level representation of a chemical equation: Ca(s) + O2(g) -> CaO(s) Assume that all spheres represent atoms of A. Which of the following is the correctly balanced equation for this reaction? A2 – 2A -> 2A – 2A + 4 – (A + A) Calcium oxide is produced when calcium reacts with oxygen in the air. Write the balanced chemical equation for this reaction: Ca(s) + O2(g) -> CaO(s) What is the sum of the coefficients? 2 Potassium fluoride is produced when potassium reacts with fluorine. Write the balanced chemical equation for this reaction. What is the coefficient for potassium? K + F2 -> KF, coefficient for potassium = 1
The Correct Answer and Explanation is:
Let’s break down the questions step by step:
1. Balancing the reaction:
The reaction between calcium and oxygen to form calcium oxide is given by: Ca (s)+O2(g)→CaO (s)\text{Ca (s)} + \text{O}_2 \text{(g)} \rightarrow \text{CaO (s)}Ca (s)+O2(g)→CaO (s)
To balance this reaction, we need to ensure that the number of atoms on both sides of the equation is the same. Here’s how we do it:
- Step 1: The left side has 1 calcium (Ca) atom, and 2 oxygen (O) atoms from the O₂ molecule. The right side has 1 calcium (Ca) atom and 1 oxygen (O) atom in the CaO.
- Step 2: To balance the oxygen atoms, we need to place a coefficient of 2 in front of CaO: Ca (s)+O2(g)→2CaO (s)\text{Ca (s)} + \text{O}_2 \text{(g)} \rightarrow 2 \text{CaO (s)}Ca (s)+O2(g)→2CaO (s)
- Step 3: Now, to balance the calcium atoms, we need to place a coefficient of 2 in front of Ca on the left side: 2Ca (s)+O2(g)→2CaO (s)2 \text{Ca (s)} + \text{O}_2 \text{(g)} \rightarrow 2 \text{CaO (s)}2Ca (s)+O2(g)→2CaO (s)
This gives us the balanced equation: 2Ca (s)+O2(g)→2CaO (s)2 \text{Ca (s)} + \text{O}_2 \text{(g)} \rightarrow 2 \text{CaO (s)}2Ca (s)+O2(g)→2CaO (s)
Answer: The coefficient for CaO in the balanced equation is 2.
2. Particulate-level representation of the reaction:
The question suggests a model where all spheres represent calcium (Ca) atoms. In this case, the balanced equation would be: 2Ca+O2→2CaO2\text{Ca} + \text{O}_2 \rightarrow 2\text{CaO}2Ca+O2→2CaO
The visual representation would show two calcium atoms reacting with one O₂ molecule to produce two CaO units.
3. Sum of the coefficients:
In the balanced equation: 2Ca (s)+O2(g)→2CaO (s)2\text{Ca (s)} + \text{O}_2 \text{(g)} \rightarrow 2\text{CaO (s)}2Ca (s)+O2(g)→2CaO (s)
The coefficients are 2 (for Ca), 1 (for O₂), and 2 (for CaO). The sum of these coefficients is: 2+1+2=52 + 1 + 2 = 52+1+2=5
Answer: The sum of the coefficients is 5.
4. Balanced equation for potassium fluoride (KF):
Potassium (K) reacts with fluorine (F₂) to form potassium fluoride (KF): K+F2→KF\text{K} + \text{F}_2 \rightarrow \text{KF}K+F2→KF
To balance the equation:
- We need 2 fluorine atoms on the left side, but the right side only has 1 fluorine in KF. So, we place a coefficient of 2 in front of KF: K+F2→2KF\text{K} + \text{F}_2 \rightarrow 2\text{KF}K+F2→2KF
- Now, to balance the potassium atoms, we place a coefficient of 2 in front of K: 2K+F2→2KF2\text{K} + \text{F}_2 \rightarrow 2\text{KF}2K+F2→2KF
Answer: The coefficient for potassium is 2.
5. Final Summary:
- The coefficient for CaO in the balanced calcium-oxygen reaction is 2.
- The sum of the coefficients in the balanced reaction is 5.
- The coefficient for potassium in the balanced potassium-fluorine reaction is 2.
