Explanation:
The mole is simply a very large number,
6.022
×
10
23
, that has a special property. If I have
6.022
×
10
23
hydrogen atoms, I have a mass of 1 gram of hydrogen atoms . If I have
6.022
×
10
23
H
2
molecules, I have a mass of 2 gram of hydrogen molecules. If I have
6.022
×
10
23
C
atoms, I have (approximately!) 12 grams.
The mole is thus the link between the micro world of atoms and molecules, and the macro world of grams and litres, the which we can easily measure by mass or volume. The masses for a mole of each element are given on the periodic table as the atomic weight. So, if have 12 g of
C
, I know, fairly precisely, how many atoms of carbon I have. Given this quantity, I know how many molecules of
O
2
are required to react
Answer:
D) 7 before and 7 after
Step-by-step explanation:
Na₂O + 2HCl ⟶ 2NaCl + H₂O
3 atoms + 4 atoms ⟶ 2×2 atoms + 3 atoms
7 atoms ⟶ 4 atoms + 3 atoms
7 atoms ⟶ 7 atoms
There are seven atoms present before and after the reaction.
The neutralization reaction is;
HClO₄(aq) + NaOH(aq) --> H₂O(l) + NaClO₄(aq)
Stoichiometry of HClO₄ to NaOH is 1:1
Therefore at equivalence an equal amount of NaOH reacts with an equal amount of HClO₄
The number of moles of NaOH in 1 L - 0.2 mol
Therefore in 21.52 ml of NaOH - 0.2/1000 x 21.52 = 0.004304 mol
the amount of HClO₄ moles that have reacted - 0.004304 mol
In 25 ml of HClO₄ - 0.004304 mol
Therefore in 1000 ml of HClO₄ - 0.004304/25 x 1000 = 0.172 mol
concentration of HClO₄ - 0.172 mol/L
The volume increases to 1.009 L.
<em>V</em>= <em>V</em>_0 +βΔ<em>T</em>
The thermal expansion coefficient (β) of water changes with temperature, so we must calculate the volume change over small (10 °C) intervals.
20 °C to 30 °C: <em>V</em> = 1 L + 0.000 207 L·°C^(-1) × 10 °C = 1.002 07 L
30 °C to 40 °C: <em>V</em> = 1.002 07 L + 0.000 303 L·°C^(-1)] × 10 °C = 1.005 10 L
40 °C to 50 °C: <em>V</em> = 1.005 10 L + 0.000 385 L·°C^(-1)] × 10 °C = 1.008 95 L
The volume increases by about 9 mL when the temperature increases from 20 °C to 50 °C.
Answer:
Carbon Tetrachloride
Explanation:
1 Carbon atom, 4 chlorine atoms (hence "tetra" prefix)
