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Scorpion4ik [409]
3 years ago
14

A 20.0 % by mass solution of phosphoric acid (H3PO4) in water has a density of 1.114 g/mL at 20°C. What is the molarity of this

solution?
Chemistry
2 answers:
saveliy_v [14]3 years ago
5 0

Answer:

Molarity is 2.272M

Explanation:

The mass % of phosphoric acid is 20.0%

It means in 100 g of solution there is 20g of phosphoric acid in it.

Molarity = moles of solute dissolved per litre of solution.

So we need volume of solution

Volume can be calculated from mass and density as

Volume = mass / Density = 100/1.114 = 89.77 mL = 0.08977 L

Moles of solute = mass of solute / molar mass of solute

moles of solute = 20g / 98 = 0.204

molarity = \frac{moles}{volume}=\frac{0.204}{0.08977} =2.272M

bogdanovich [222]3 years ago
3 0
Assume you have 1 L of the material (you can assume any volume you want, you'll get the same answer). 

<span>Using the density, the one L has a mass of 1114 g </span>

<span>20% by mass of phosphoric acid means the mass of phosphoric acid is 0.20 * 1114 g </span>

<span>Calculate the moles of phosphoric acid </span>

<span>Molarity, M, mole / L = moles of acid / volume or 1 L</span>
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At STP, a 50.-gram sample of H2O(l) and a 100.-gram sample of H2O(1) have
LiRa [457]

Answer:

The same chemical properties

Explanation:

Different masses of water at the same temp and pressure will have different volumes and the same empirical formulas and the same chemical properties

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2 years ago
11. The oxyfuel flame was used for fusion welding as early as the first half of the
Firlakuza [10]

The Oxyfuel gas or flame refers to a group of welding processes that use the flame produced by the combination of a fuel gas and oxygen as the source of heat.

<u>Explanation:</u>

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7 0
3 years ago
How much heat in kj is released by burning 9.5 grams of methane?
tatyana61 [14]
Methane is the compound CH4, and burning it uses the reaction:

CH4 + O2 -> CO2 + H2O, which is rather exothermic. To find the heat released by burning a certain amount of the substance, you should look at the bond enthalpy of each compound, and then compare the values before and after the reaction. In methane, there are 4 C-H bonds, which have bond energy of 416 kj/mol, resulting in a total bond energy of 1664 kj/mol. O2 is 494 kj/mol. Therefore we have a total of 2080 kj/mol on the left side. On the right side we have CO2, which has 2 C=O bonds, each at 799 kj/mol each, resulting in 1598 kj/mol, and H2O has 2 O-H bonds, at 459kj/mol each, resulting in a total of 2516 kj/mol on the right hand side. Now, this may be confusing because the left hand side seems to have less heat than the right, but you just need to remember: making minus breaking, which results in a total change of 436kj/mol heat evolved.

Now it is a simple matter of find the mols of CH4 reacted, using n=m/mr.

n = 9.5/16.042 = 0.592195 mol

Therefore, if we reacted 0.592195 mol, and we produced 436 kj for one mol, the total amount of energy evolved was 436*<span>0.592195 kj, or 258.197 kj.</span>
7 0
3 years ago
Why does the pressure inside a container of gas increase?
yan [13]
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3 0
3 years ago
Group 2A metal oxides react with water to produce hydroxides. When 35.55 g of CaO are placed into 125 mL of water (d= 1.000 g/mL
Vika [28.1K]
Answer is: mass of calcium hydroxide is 46.98 grams.
Balanced chemical reaction: CaO + H₂O → Ca(OH)₂.
m(CaO) = 35.55 g.
n(CaO) = m(CaO) ÷ M(CaO).
n(CaO) = 35.55 g ÷ 56 g/mol.
n(CaO) = 0.634 mol; limiting reactant.
m(H₂O) = 125 mL · 1.000 g/mL.
m(H₂O) = 125 g.
n(H₂O) = 125 g ÷ 18 g/mol.
n(H₂O) = 6.94 mol.
From chemical reaction: n(CaO) : n(Ca(OH)₂) = 1 : 1.
n(Ca(OH)₂) = 0.634 mol.
m(Ca(OH)₂) = 0.634 mol · 74.1 g/mol = 46.98 g.
5 0
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