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3 years ago

What is the coldest temperature ever achieved?

Chemistry

2 answers:

Georgia [21]3 years ago

8 0

For the whole world, the lowest temperature on earth was recorded at -128.6 degrees in Russia. This was in July of 1983

kupik [55]3 years ago

5 0

Answer:

The lowest natural temperature ever directly recorded at ground level on Earth is −89.2 °C

-273.144 degrees celsius. This is close to 'absolute zero', which is equal to -273.15 degrees celsius

Explanation:

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Which of the following best describes a single-replacement reaction?

blondinia [14]

Answer

B. One element takes the place of another in a compound

Explanation

A single-replacement reaction occurs when one element is substituted for another element in a compound.The reacting materials are normally pure elements such as a metal or hydrogen gas with an aqueous compound.A new aqueous compound plus a different pure element are formed as products.

6 0

3 years ago

Read 2 more answers

What is the ionic equation of Aqueous calcium bromide was mixed with aqueous gold(I) perchlorate, and a crystallized gold(I) bro

Bumek [7]

Answer:- $2AuClO_4(aq) + CaBr_2(aq)\rightarrow 2AuBr(s)+ Ca(ClO_4)_2(aq)$

Explanations:- It's a double replacement reaction where a precipitate of silver(I)bromide is formed. A dpuble replacement reaction in general looks as AB + CD \rightarrow AD + CB

To balance the equation we need to multiply gold compounds on both sides by 2 and the balanced equation is..

$2AuClO_4(aq) + CaBr_2(aq)\rightarrow 2AuBr(s)+ Ca(ClO_4)_2(aq)$

6 0

3 years ago

Cryolite, Na3AlF6(s), an ore used in the production of aluminum, can be synthesized using aluminum oxide. Balance the equation f

dmitriy555 [2]

Answer: The mass of cryolite produced is 51.48 kg

Explanation:

To calculate the number of moles, we use the equation:

$\text{Number of moles}=\frac{\text{Given mass}}{\text{Molar mass}}$ .....(1)

For aluminium oxide:

Given mass of aluminium oxide = 12.5 kg = 12500 g (Conversion factor: 1 kg = 1000 g)

Molar mass of aluminium oxide = 101.96 g/mol

Putting values in equation 1, we get:

$\text{Moles of aluminium oxide}=\frac{12500g}{101.96g/mol}=122.6mol$

For NaOH:

Given mass of NaOH = 55.4 kg = 55400 g

Molar mass of NaOH = 40 g/mol

Putting values in equation 1, we get:

$\text{Moles of NaOH}=\frac{55400g}{40g/mol}=1389mol$

For HF:

Given mass of HF = 55.4 kg = 55400 g

Molar mass of HF = 20 g/mol

Putting values in equation 1, we get:

$\text{Moles of HF}=\frac{55400g}{20g/mol}=2770mol$

For the given chemical reaction:

$Al_2O_3(s)+6NaOH(l)+12HF(g)\rightarrow 2Na_3AlF_6+9H_2O(g)$

By Stoichiometry of the reaction:

1 mole of aluminium oxide reacts with 6 moles of sodium hydroxide and 12 moles of HF.

So, 122.6 moles of aluminium oxide will react with $(6\times 122.6)=735.6mol$ of sodium hydroxide and $(12\times 122.6)=1471.2mol$ of HF

As, given amount of NaOH and HF is more than the required amount. So, they are considered as an excess reagent.

Thus, aluminium oxide is considered as a limiting reagent because it limits the formation of product.

By Stoichiometry of the reaction:

1 mole of aluminium oxide produces 2 moles of cryolite

So, 122.6 moles of aluminium oxide will produce = $\frac{2}{1}\times 122.6=245.2mol$ of cryolite

Now, calculating the mass of cryolite by using equation 1:

Molar mass of cryolite = 209.94 g/mol

Moles of cryolite = 245.2 mol

Putting values in equation 1, we get:

$245.2mol=\frac{\text{Mass of cryolite}}{209.94g/mol}\\\\\text{Mass of cryolite}=(245.2mol\times 209.94g/mol)=51477.3g$

Converting this into kilograms, we use the conversion factor:

1 kg = 1000 g

So, $51477.3 g\times (\frac{1kg}{1000g})=51.48kg$

Hence, the mass of cryolite produced is 51.48 kg

7 0

3 years ago

How many moles of H2O form when 4.5 moles O2 reacts?

mart [117]

Explanation:

Start with a balanced equation.

2H2 + O2 → 2H2O

Assuming that H2 is in excess, multiply the given moles H2O by the mole ratio between O2 and H2O in the balanced equation so that moles H2O cancel.

5 mol H2O × (1 mol O2/2 mol H2O) = 2.5 mol O2

Answer: 2.5 mol O2 are needed to make 5 mol H2O, assuming H2 is in excess.

4 0

3 years ago

Why does fluorine have the highest electronegativity

ICE Princess25 [194]

Answer:

Because it only needs one more electron to get to a full valence shell (8), so it really wants it and is pulling other electrons in. It also has to do with needing one more electron to fill the 2p shell. It is a small element which means its electrons are pulled tightly to the nucleus.

Hope this helps!

Explanation:

5 0

2 years ago