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2 years ago

Which of the following are pure substances? (Select all that apply.)

1 answer:

riadik2000 [5.3K]2 years ago

6 0

Elements and compounds are both examples of pure substances. Compounds are substances that are made up of more than one type of atom. Elements are the simplest substances made up of only one type of atom. i hope that helps:)

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A mining company wants to build a modern processing plant that is safe for workers.

777dan777 [17]

To determine the level of radionuclides present

3 0

3 years ago

How would you prepare 500 ml of the following solutions : Sodium succinate buffer (0.1 mol/dm3 pH 5.64)

Nana76 [90]

Answer:

8.10g of sodium succinate must be added and 247mL of 0.1M HCl adding enough water until make 500mL

Explanation:

Succinic acid has a pKa₂ of 5.63

To solve this question we must find the amount of sodium succinate and 0.1M HCl that we have to add using H-H equation:

pH = pKa + log [A-] / [HA]

5.64 = 5.63 + log [Na₂Succ.] / [HSucc⁺]

0.01 = log [Na₂Succ.] / [HSucc⁺]

1.0233 = [Na₂Succ.] / [HSucc⁺] (1)

As:

0.1M = [Na₂Succ.] + [HSucc⁺] (2)

Replacing (2) in (1):

1.0233 = 0.1M - [HSucc⁺] / [HSucc⁺]

1.0233[HSucc⁺] = 0.1M - [HSucc⁺]

2.033[HSucc⁺] = 0.1M

[HSucc⁺] = 0.0494M

[Na₂Succ] = 0.0506M

Both [Na₂Succ⁺] and [HSucc⁺] ions comes from the same sodium succinate we have to find the moles of sodium succinate in 500mL of 0.1M. Then, based on the reaction:

Na₂Succ + HCl → HSucc⁺ + Cl⁻

The moles of HCl added = Moles HSucc⁺ we need:

Moles Na₂Succ:

0.500L * (0.1mol/L) = 0.0500 moles

Mass -Molar mass sodium succinate: 162.05g/mol-:

0.0500mol * (162.05g/mol) = 8.10g of sodium succinate must be added

Moles HCl:

0.0494M * 0.500L = 0.0247 moles HCl * (1L / 0.1mol) = 0.247L =

And 247mL of 0.1M HCl adding enough water until make 500mL

7 0

3 years ago

Balance this equation

laila [671]

Answer:

4HCl + SiO2 → 4H2O + SiCl4

axit clohidric Silic dioxit nước Silic tetraclorua

Axit

Explanation:

5 0

2 years ago

Read 2 more answers

What is the energy produced through cellular respiration called?

tresset_1 [31]

Answer:

During the process of glycolysis in cellular respiration, glucose is oxidized to carbon dioxide and water. Energy released during the reaction is captured by the energy-carrying molecule ATP (adenosine triphosphate).

4 0

3 years ago

Which of the following statements best describes why carbon can form a variety of organic compounds? Carbon atoms bond readily w

olga_2 [115]

Answer:
Carbon readily forms covalent bonds with other carbon atoms.

Explanation:
As we know approximately more than 95 % compounds, either isolated, discovered or synthesized belongs to organic compounds containing carbon atoms.
This great diversity of organic compounds is due to following facts.

1) Catenation:
Carbon has a peculiar behavior of self linkage. This self linkage of one carbon with another is called as catenation. In this way carbon can form a long chain of carbon atom. A branching can also take place when one carbon is bonded further to three of four carbon atoms.

2) Isomerism:
Secondly the carbon containing compounds show isomerism. In which molecular formula is same but structural formula is different. For example molecular formula C₅H₁₂ can make following compounds,

a) n-Pentane

b) 2-Methylbutane

c) 2,2-Dimethylpropane

3) Multiple Bonds:
Carbon can form multiple bonds i.e double bond like in alkenes and triple bonds like in alkyne.

Due to these factors carbon gets very high number of opportunities to form large number of compounds.

7 0

3 years ago