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3 years ago

What was helium used for in the past?

Chemistry

2 answers:

yawa3891 [41]3 years ago

6 0

Helium used to be used in hot air balloons. Then, when the Hindenburg exploded, annexed file, they realized that hydrogen was not only lighter, but it also was less flammable.

Otrada [13]3 years ago

3 0

Hot air balloons. They have a little hot plate/fire or whatever and they used, and that made the helium rise, thus rising the balloon.

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CaCl2 (picture) i don’t know how to do the problem

Vadim26 [7]

Answer:

Ca: 1

Cl: 2

Explanation:

Since there is no subscript but there is the element, its assumed that there is at least 1, otherwise it would'nt be there

8 0

3 years ago

Aluminum–lithium (Al–Li) alloys have been developed by the aircraft industry to reduce the weight and improve the performance of

gtnhenbr [62]

Answer:

The concentration of Li (in wt%) is 3,47g/mol

Explanation:

To obtain the 2,42g/cm³ of density:

2,42g/cm³ = 2,71g/cm³X + 0,534g/cm³Y (1)

Where X is molar fraction of Al and Y is molar fraction of Li.

X + Y = 1 (2)

Replacing (2) in (1):

Y = 0,13

Thus, X = 0,87

The weight of Al and Li is:

0,87*26,98g/mol = 23,4726 g of aluminium

0,13*6,941g/mol = 0,84383 g of lithium

The concentration of Li (in wt%) is:

0,84383g/(0,84383g+23,4726g) ×100= 3,47%

6 0

2 years ago

1,280 Cal into kilojoules

Simora [160]

Because energy need to be Times 4. Not sure if I helped you

3 0

3 years ago

What causes a lunar eclipse? Why doesn't a lunar eclipse occur during each full moon?

Marta_Voda [28]

A lunar eclipse occurs when the Earth moves between the Moon and the Sun. a lunar eclipse does not occur during each full moon because the earth does not cross between the sun and the moon, it does not always happen. Also, a lunar eclipse doe not have to happen on a full moon, they are two different phenomenas .

3 0

3 years ago

Write a net ionic equation to show why solid lithium hydroxide, lioh (s), forms a basic solution when it dissolves in water.

Doss [256]

Solid lithium oxide, the basic anhydride of lithium hydroxide reacts with water to make lithium ions and hydroxide ions. Li2O(s) + H2O(l) --> 2LiOH(aq) ...... molecular equation Li2O(s) + H2O(l) --> 2Li+ + 2OH- ..... ionic equation, and net ionic equation BUT!!!!! The decomposition of potassium chlorate into KCl and O2 gas does not take place in aqueous solution. The equation should be. 2KClO3(s) --> 2KCl(s) + 3O2(g) No ionic equation. There is nothing in solution. This reaction does not occur in aqueous solution. 2Na(s) + I2(g) --> 2NaI(s) No ionic equation. There is nothing in solution. Clearly, to have an ionic equation there must be ions, and to have ions the salts have to be dissolved in water.

5 0

3 years ago