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padilas [110]
3 years ago
11

What was discovered first helium or samarium?

Chemistry
1 answer:
lana [24]3 years ago
7 0
The correct answer is helium, but both discoveries were quite close. Helium was discovered in 1868 during a solar eclipse by French astronomer Jules Janssen, while samarium was discovered in 1879 by a French chemist Paul Émile Lecoq de Boisbaudran.
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Explanation: see attachment below

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3 years ago
How many grams of oxygen are produced when 7.65 moles of water is decomposed
maksim [4K]

Answer:

The answer to your question is 122.4 g of O₂

Explanation:

Data

mass of O₂ = ?

moles of H₂O = 7.65

Process

1.- Write the balanced chemical reaction

                   2H₂O  ⇒  2H₂  +  O₂

2.- Convert the moles of H₂O to grams

molar mass of H₂O = 2 + 16 = 18 g

                    18 g of H₂O ---------------- 1 mol

                      x                ----------------- 7.65 moles

                      x = (7.65 x 18) / 1

                      x = 137.7 g H₂O

3.- Calculate the grams of O₂

                 36 g of H₂O -------------------- 32 g of O₂

              137.7 g of H₂O -------------------  x

                        x = (32 x 137.7) / 36

                       x = 122.4 g of O₂

 

6 0
3 years ago
Need help with this question plsssss
GaryK [48]

Answer:

234

Explanation:

8 0
2 years ago
When the particles of a gas decrease in energy what happens?
NeTakaya
It changes to a liquid
3 0
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