Answer:
<u> Translation:</u>
Classify the following elements into metals, nonmetals, metalloids, or gases, noble
: fluorine, sulfur, nitrogen, chlorine, magnesium, helium, sodium, bromine, silicon, tellurium.
- Metals: magnesium and sodium.
- Nonmetals: fluorine, chlorine, bromine, sulfur and nitrogen.
- Metalloids: silicon and tellurium.
- Noble gases: helium.
Explanation:
Metals: They occupy the left and central areas of the Periodic Table; therefore, they constitute a majority group of the elements.
Nonmetals: They are located in the upper right region of the Periodic Table.
Within the Periodic Table, the metalloids lie diagonally from boron to polonium. Items above on the right are nonmetals, and items below on the left are metals.
The noble gases are located in group 18 of the Periodic Table.
Answer:
1. Cu
2. Cu
3. 2 electrons.
Explanation:
Step 1:
The equation for the reaction is given below:
3Cu(s) + 8HNO3(aq) -> 2NO(g) 3Cu(NO3)2(aq) + 4H2O(l)
Step 2:
Determination of the change of oxidation number of each element present.
For Cu:
Cu = 0 (ground state)
Cu(NO3)2 = 0
Cu + 2( N + 3O) = 0
Cu + 2(5 + (3 x -2)) =0
Cu + 2 (5 - 6) = 0
Cu + 2(-1) = 0
Cu - 2 = 0
Cu = 2
The oxidation number of Cu changed from 0 to +2
For N:
HNO3 = 0
H + N + 3O = 0
1 + N + (3 x - 2) = 0
1 + N - 6 = 0
N = 6 - 1
N = 5
NO = 0
N - 2 = 0
N = 2
The oxidation number of N changed from +5 to +2
The oxidation number of oxygen and hydrogen remains the same.
Note:
1. The oxidation number of Hydrogen is always +1 except in hydride where it is - 1
2. The oxidation number of oxygen is always - 2 except in peroxide where it is - 1
Step 3:
Answers to the questions given above
From the above illustration,
1. Cu is oxidize because its oxidation number increased from 0 to +2 as it loses electron.
2. Cu is the reducing agent because it reduces the oxidation number of N from +5 to +2.
3. The reducing agent i.e Cu transferred 2 electrons to the oxidising agent HNO3 because its oxidation number increase from 0 to +2 as it loses its electrons. This means that Cu transfer 2 electrons.
x = 20 long tables
y = 5 round table
Explanation:
We have the following system of equations:
x + y = 25
8x + 6y = 190
From the first equation we have:
x = 25 - y
And we replace x in the second equation:
8(25 - y) + 6y = 190
200 - 8y + 6y = 190
200 - 2y = 190
200 - 190 = 2y
10 = 2y
y = 5
Now we insert the value of y in the next equation:
x = 25 - y
x = 25 - 5
x = 20
Learn more about:
system of equations
brainly.com/question/1748197
brainly.com/question/1658819
#learnwithBrainly
So basically, the change in color effects the amount of cations in the solution making it a physical change rather than a chemical one, defying the law of conservation of mass! I hope this helped! (The only time the change in color affects the amount of cations is in the Alkaline Earth Metals)
source: college science teacher
