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natulia [17]
3 years ago
7

How are you finding the moles of the unknown substance when you are only given the grams of the unknown molecular compound?

Chemistry
1 answer:
Natali [406]3 years ago
4 0

Answer:

Determine the moles of unknown (the solute) from the molality of the solution and the mass of solvent (in kilograms) used to make the solution. Determine the molar mass from the mass of the unknown and the number of moles of unknown.

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A mass of 100.0 g of NaCl is added to 100.0 mL of water, but not all of it dissolves. A mass of 59.5 grams of NaCl solid remains
Taya2010 [7]

Answer:

The molarity of the dissolved NaCl is 6.93 M

Explanation:

Step 1: Data given

Mass of NaCl = 100.0 grams

Volume of water = 100.0 mL = 0.1 L

Remaining mass NaCl = 59.5 grams

Molar mass NaCl= 58.44 g/mol

Step 2: Calculate the dissolved mass of NaCl

100 - 59. 5 = 40.5 grams

Step 3: Calculate moles

Moles NaCl = 40.5 grams / 58.44 g/mol

Moles NaCl = 0.693 moles

Step 4: Calculate molarity

Molarity = moles / volume

Molarity dissolved NaCl = 0.693 moles / 0.1 L

Molarity dissolved NaCl = 6.93 M

The molarity of the dissolved NaCl is 6.93 M

8 0
2 years ago
Read 2 more answers
Deterioration of buildings, bridges, and other structures through the rusting of iron costs millions of dollars a day. The actua
GrogVix [38]

The value of ∆H when 0.250kg of iron rusts is -1.846 × 10³kJ.

The rust forms when 4.85X10³ kJ of heat is released is 888.916 g.

<h3>Chemical reaction:</h3>

4 Fe + 3O2 ------ 2Fe2O3

∆H = -1.65×10³kJ

A) Given,

mass of iron = 0.250kg = 250 g

<h3>Calculation of number of moles</h3>

moles = given mass/ molar mass

= 250/ 55.85 g/mol.

= 4.476 mol

As we know that,

For the rusting of 4 moles of Fe, ∆H = -1.65×10³kJ

For the rusting of 4.476 moles of Fe ∆H required can be calculated as

-1.65×10³kJ × 4.476 mol/ 4mol

∆H required = -1.846 × 10³kJ

Now,

when 2 mol of Fe2O3 formed, ∆H = - 1.65×10³kJ

It can be said that,

-1.65×10³kJ energy released when 2 mol of Fe2O3 formed

So, -4.6 × 10³kJ energy released when 2 mol of Fe2O3 formed

= 2 × -4.6 × 10³kJ / -1.65×10³kJ

= 5.57 mol of Fe2O3 formed

Now,

mass of Fe2O3 formed = 5.57 mol × 159.59 g/mol

= 888.916 g

Thus, we calculated that the rust forms when 4.85X10³ kJ of heat is released is 888.916 g. and the value of ∆H when 0.250kg of iron rusts is -1.846 × 10³kJ.

learn more about ∆H:

brainly.com/question/24170335

#SPJ4

DISCLAIMER:

The given question is incomplete. Below is the complete question

QUESTION:

Deterioration of buildings, bridges, and other structures through the rusting of iron costs millions of dollars a day. The actual process requires water, but a simplified equation is 4Fe(s) + 3O₂(g) → 2Fe₂O₃(s) ΔH = -1.65×10³kJ

a) What is the ∆H when 0.250kg iron rusts.

(b) How much rust forms when 4.85X10³ kJ of heat is released?

7 0
1 year ago
Balance the equation of. _C + _O2 -- _CO
scoundrel [369]

Explanation:

2C +O2 = 2CO

this will be the answer

8 0
2 years ago
Which is the most important question for deciding if a chemical reaction has occurred?
777dan777 [17]

Answer:

all these are physical properties except release of heat so it's probably heat energy given off

7 0
3 years ago
Read 2 more answers
What is the photoelectric effect?
scZoUnD [109]
It's the emission of an electron when lights hit metal! Hope that helps! :)
7 0
3 years ago
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