. What is the mass, in grams, of a sample of 7.83 × 1024 atoms of helium (He)?

Chemistry

1 answer:

erica [24]3 years ago

6 0

Moles He = 7.83 x 10^24 / 6.02 x 10^23 =13.0

<span>mass He = 13.0 mol x 4.00 g/mol = 52.0 g</span>

You might be interested in

What process transform solar energy into chemical energy?

DIA [1.3K]

Green plants transform solar energy<span> to </span>chemical energy<span> (mostly of oxygen) through the </span>process<span> known as photosynthesis, and electrical </span>energy<span> can be converted to </span>chemical energy<span> and vice versa through electrochemical reactions.</span>

8 0

2 years ago

(part 1 of 3) Copper reacts with silver nitrate through a single replacement. If 1.29 g of silver are produced from the reaction

ale4655 [162]

Answer:

See explanation.

Explanation:

Hello there!

In this case, according to the described chemical reaction, we first write the corresponding equation to obtain:

$Cu+2AgNO_3\rightarrow 2Ag+Cu(NO_3)_2$

Thus, we proceed as follows:

Part 1 of 3: here, since the molar mass of silver and copper (II) nitrate are 107.87 and 187.55 g/mol respectively, and the mole ratio of the former to the latter is 2:1, we can set up the following stoichiometric expression:

$m_{Cu(NO_3)_2}=1.29gAg*\frac{1molAg}{107.87gAg}*\frac{1molCu(NO_3)_2}{2molAg}*\frac{187.55gCu(NO_3)_2}{1molCu(NO_3)_2} \\\\m_{Cu(NO_3)_2}=1.12gCu(NO_3)_2$

Part 2 of 3: here, the molar mass of copper is 63.55 g/mol and the mole ratio of silver to copper is 2:1, the mass of the former that was used to start the reaction was:

$m_{Cu}=1.29gAg*\frac{1molAg}{107.87gAg}*\frac{1molCu}{2molAg}*\frac{63.55gCu)_2}{1molCu} \\\\m_{Cu}=0.380gCu$