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olasank [31]
3 years ago
7

Pablo wants to enter the science fair. Which question could be answered through scientific investigation?

Chemistry
2 answers:
Oliga [24]3 years ago
7 0

Answer:

Hello

Explanation:

utd847dcpyc08td0

Ilya [14]3 years ago
7 0
What’s the question?
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In chemistry, what varies with the number of molecules present in a sample of a particular substance?
Neko [114]

Answer: concentration

Explanation:

Concentration refers to the amount of a substance present in a sample. The more molecules of a substance present in a sample, the greater its concentration. The less molecules of a substance in a sample, the lesser the concentration. We are often concerned about analytically determining the concentration of a substance using diverse analytical methods in chemistry.

3 0
3 years ago
How many grams of KCl is needed to make .75 L of a 1 M solution of KCl?
Zielflug [23.3K]

Answer:

The answer to your question is 25.9 g of KCl

Explanation:

Data

Grams of KCl = ?

Volume = 0.75 l

Molarity = 1 M

Formula

Molarity = \frac{number of moles}{volume}

Solve for number of moles

Number of moles = Molarity x volume

Substitution

Number of moles = 1 x 0.75

Simplification

Number of moles = 0.75 moles

Molecular mass KCl = 39 + 35.5 = 34.5

Use proportions to find the grams of KCl

                          34.5 g of KCl ----------------  1 mol

                             x                  ----------------  0.75 moles

                            x = (0.75 x 34.5) / 1

                            x = 25.9 g of KCl

3 0
3 years ago
Can someone please help me with the with this
solong [7]

Answer:

Chemical

Explanation:

4 0
3 years ago
Using the following reaction (depicted using molecular models), large quantities of ammonia are burned in the presence of a plat
Mila [183]

Answer:

17.65 grams of O2 are needed for a complete reaction.

Explanation:

You know the reaction:

4 NH₃ + 5 O₂ --------> 4 NO + 6 H₂O

First you must know the mass that reacts by stoichiometry of the reaction (that is, the relationship between the amount of reagents and products in a chemical reaction). For that you must first know the reacting mass of each compound. You know the values ​​of the atomic mass of each element that form the compounds:

  • N: 14 g/mol
  • H: 1 g/mol
  • O: 16 g/mol

So, the molar mass of the compounds in the reaction is:

  • NH₃: 14 g/mol + 3*1 g/mol= 17 g/mol
  • O₂: 2*16 g/mol= 32 g/mol
  • NO: 14 g/mol + 16 g/mol= 30 g/mol
  • H₂O: 2*1 g/mol + 16 g/mol= 18 g/mol

By stoichiometry, they react and occur in moles:

  • NH₃: 4 moles
  • O₂: 5 moles
  • NO: 4 moles
  • H₂O: 6 moles

Then in mass, by stoichiomatry they react and occur:

  • NH₃: 4 moles*17 g/mol= 68 g
  • O₂: 5 moles*32 g/mol= 160 g
  • NO: 4 moles*30 g/mol= 120 g
  • H₂O: 6 moles*18 g/mol= 108 g

Now to calculate the necessary mass of O₂ for a complete reaction, the rule of three is applied as follows: if by stoichiometry 68 g of NH₃ react with 160 g of O₂, 7.5 g of NH₃ with how many grams of O₂ will it react?

mass of O_{2} =\frac{7.5 g of NH_{3} * 160 g of O_{2} }{68 g of NH_{3} }

mass of O₂≅17.65 g

<u><em>17.65 grams of O2 are needed for a complete reaction.</em></u>

3 0
3 years ago
The experimental procedure has you wash your thermometer and dry it after you measure the temperature of naoh solution and befor
Rzqust [24]
<span>If you do not wash and dry the thermometer after every time you use it in this scenario, the temperature could be affected by the NaOH residue. This could make it so that your findings were inaccurate, so in order to be efficient, this precaution needs to be taken.</span>
6 0
3 years ago
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