Let us assume that there is a 100g sample of Opal. The masses of each element will be:
29.2g Si
33.3g O
37.5g H2O
Now we divide each constituent's mass by its Mr to get the moles present
Si: (29.2 / 28) = 1.04
O: (33.3 / 16) = 2.08
H2O: (37.5 / 18) = 2.08
Now we divide by the smallest number and obtain:
Si: 1
O: 2
H2O: 2
Thus, the empirical formula of Opal is:
SiO2 . 2H2O
Answer:How many ions are in 2 moles of NaCl?
2 mol NaCl = 2 x 6.02 x 10 23 = 1.204 x 10 24 NaCl formula units 2 mol NaCl = 2 (2 x 6.02 x 10 23 )= 2 (1.204 x 10 24) = 2.408 x 10 24 atoms *2 moles of sodium chloride contains 2.408 x 10 24 ions (combination of Na + ions & Cl – ions). H
Explanation:
sorry i was running out of time
8 valence electrons are found in noble gases. Since noble gases have 8 valence electrons that means they have a full shell - which makes them unreactive
Answer:
d. 4 Al(s) + 3 O₂(g) → 2 Al₂O₃(s)
Explanation:
Aluminum metal reacts with oxygen gas in a combination reaction that forms a product that coats the metal preventing it from further oxidation: aluminum oxide. Aluminum is a cation with charge 3+ (Al³⁻) and oxide is an anion with charge 2- (O²⁻). Thus, the neutral compound aluminum oxide has the chemical formula Al₂O₃. The unbalanced chemical equation is:
Al(s) + O₂(g) → Al₂O₃(s)
We can balance using the trial and error method. First, we will balance O atoms by multiplying Al₂O₃ by 2 and O₂ by 3.
Al(s) + 3 O₂(g) → 2 Al₂O₃(s)
Finally, we get the balanced equation by multiplying Al by 4.
4 Al(s) + 3 O₂(g) → 2 Al₂O₃(s)
Answer:
The speed is positive either direction.
Explanation:
- It is given that, a vehicle travels at the same speed from point A to point B then from point B to point A.
- We know that speed is a scalar quantity and velocity is a vector quantity.
- Speed has only magnitude while velocity have both magnitude as well as direction.
- In this case, the vehicle will have positive speed in either direction.
- Hence, the correct option is (D)
