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nata0808 [166]
2 years ago
13

The graduated cylinder below shows major scale divisions every 5 mL. How should the volume of the liquid be recorded? Use the co

rrect number of significant figures.

Chemistry
1 answer:
OLga [1]2 years ago
6 0

Explanation:

First, note that the surface of the liquid is curved. This is called the meniscus. This phenomenon is caused by the fact that water molecules are more attracted to glass than to each other (adhesive forces are stronger than cohesive forces). When we read the volume, we read it at the BOTTOM of the meniscus.

The smallest division of this graduated cylinder is 1 mL. Therefore, our reading error will be 0.1 mL or 1/10 of the smallest division. An appropriate reading of the volume is 36.5 0.1 mL. An equally precise value would be 36.6 mL or 36.4 mL.

How many significant figures does our answer have? 3! The "3" and the "6" we know for sure and the "5" we had to estimate a little.

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Karla added green pellets to a container of water before she began watering her lawn. What correctly describes
kvv77 [185]

The correct answer is C. The water is the solvent because the green pellets dissolved in it.

Explanation:

In solutions, the are two substances involved, the solvent and the solute. The solvent is usually a liquid substance; additionally, the solvent dissolves another substance, which is known as the solute. For example, if you dissolve a spoon of salt in a glass of water, the solute is the salt which is the substance dissolved and the solvent is the water because the solute is dissolved in it. According to this, in the case presented the water is the solvent because the green pellets which are the solute dissolve in it.

5 0
3 years ago
The heat of vaporization of water is 40.66 kJ/mol. How much heat is absorbed when 3.11 g of water boils at atmospheric pressure?
Roman55 [17]

Answer:

The amount of heat that is absorbed when 3.11 g of water boils at atmospheric pressure is 7.026 kJ.

Explanation:

A molar heat of vaporization of 40.66 kJ / mol means that 40.66 kJ of heat needs to be supplied to boil 1 mol of water at its normal boiling point.

To know the amount of heat that is absorbed when 3.11 g of water boils at atmospheric pressure, the number of moles represented by 3.11 g of water is necessary. Being:

  • H: 1 g/mole
  • O: 16 g/mole

the molar mass of water is:

H₂O= 2* 1 g/mole + 16 g/mole= 18 g/mole

So: if 18 grams of water are contained in 1 mole, 3.11 grams of water in how many moles are present?

moles of water=\frac{3.11 grams*1 mole}{18 gramos}

moles of water= 0.1728

Finally, the following rule of three can be applied: if to boil 1 mole of water at its boiling point it is necessary to supply 40.66 kJ of heat, to boil 0.1728 moles of water, how much heat is necessary to supply?

heat=\frac{0.1728 moles*40.66 kJ}{1 mole}

heat= 7.026 kJ

<u><em>The amount of heat that is absorbed when 3.11 g of water boils at atmospheric pressure is 7.026 kJ.</em></u>

7 0
3 years ago
Linolenic acid (C18H30O2 - M.W. = 278.42 g/mol) reacts with hydrogen gas according to the equation: C18H30O2 + 3H2 (g) → C18H36O
Ludmilka [50]

Answer:

2.53 L is the volume of H₂ needed

Explanation:

The reaction is: C₁₈H₃₀O₂ + 3H₂ → C₁₈H₃₆O₂

By the way we can say, that 1 mol of linolenic acid reacts with 3 moles of oxygen in order to produce, 1 mol of stearic acid.

By stoichiometry, ratio is 1:3

Let's convert the mass of the linolenic acid to moles:

10.5 g . 1 mol / 278.42 g  = 0.0377 moles

We apply a rule of three:

1 mol of linolenic acid needs 3 moles of H₂ to react

Then, 0.0377 moles will react with (0.0377 . 3 )/1 = 0.113 moles of hydrogen

We apply the Ideal Gases Law to find out the volume (condition of measure are STP) → P . V = n . R . T → V = ( n . R .T ) / P

V = (0.113 mol . 0.082 L.atm/mol.K . 273.15K) 1 atm = 2.53 L

4 0
3 years ago
How does knowing the equivalence point for a titration help pick out an indicator?
Gnoma [55]
Answer is: near equivalence point indicator should change color, so we must pick indicator who changes color near pH of equivalence point.
Equivalence point is the point which there is stoichiometrically equivalent amounts of acid and base. <span>
<span>Chemist can draw pH curve (graph showing the change in pH of a solution, which is being titrated) for titration and determine equivalence point.</span></span>
6 0
3 years ago
Why are the current borders of the Middle East different than
Jlenok [28]

Answer:

Belgium and the Netherlands swap land near Lanaye and Oost-Maarland over the discovery of a headless body several years prior, which the Belgian Authorities could not access without crossing Dutch territory. The border has been straightened out and now runs down the center of the Meuse River.[5] The change took effect on 1 January 2018.

Explanation:

5 0
3 years ago
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