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Debora [2.8K]
3 years ago
15

PLEASE HELP(2 questions)!!!!! BRAINLIEST IF FIRST AND CORRECTLY ANSWERED!!!

Chemistry
1 answer:
professor190 [17]3 years ago
8 0
D
B
those are the correct answers
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What are the molality and mole fraction of solute in a 35.9 percent by mass aqueous solution of formic acid (HCOOH)?
sdas [7]

ِAnswer:

1- The molarity of HCOOH = 9.515 M.

2- The mole fraction of HCOOH = 0.18.

Explanation:

<em>1- The molarity of HCOOH:</em>

  • We can calculate the molarity of HCOOH using the relation:

M = (10pd)/molar mass.

p is the percent by mass of HCOOH = 35.9 %.

d is the specific gravity of HCOOH = 1.22 g/cm³.

Molar mass of HCOOH = 46.03 g/mol.

∴ M = (10pd)/molar mass = (10)(35.9 %)(1.22 gcm³) / (46.03 g/mol) = 9.515 M.

<em>2- The mole fraction of HCOOH:</em>

  • We can suppose that we have a 100 g solution, that contains 35.9 g of HCOOH and 64.1 g of water.

<em>The mole fraction of HCOOH = (no. of moles of HCOOH) / (no. of moles of HCOOH + no, of moles of water).</em>

no. of moles of HCOOH = mass / molar mass = (35.9 g)/(46.03 g/mol) = 0.78 mol.

no. of moles of water = mass / molar mass = (64.1 g)/(18.0 g/mol) = 3.56 mol.

  • The mole fraction of HCOOH = (no. of moles of HCOOH) / (no. of moles of HCOOH + no, of moles of water) = (0.78 mol) / (0.78 mol + 3.56 mol) = 0.18.
7 0
3 years ago
What happens when a beaker with cold water is held in a yellow burner flame? Explain this.​
schepotkina [342]
The flame that comes out of the Bunsen burner. it's blue/pale violet.
7 0
2 years ago
How many moles are in 7.8g of CaO?
Bess [88]

This compound is also known as Calcium Oxide. The SI base unit for amount of substance is the mole. 1 grams CaO is equal to 0.017832495800447 mole. Note that rounding errors may occur, so always check the results.

Hope I helped :)

4 0
2 years ago
Good evening! Does anyone know this? Earth Science
riadik2000 [5.3K]

The fraction of Earth's radius (6371 km) relative to the thickness of the oceanic (7.5 km) and continental crust (35 km) is 0.12 and 0.55, respectively.    

What we know:

  • The average radius of Earth (E) = 6371 km
  • The average thickness of oceanic crust (O) = 7.5 km
  • The average thickness of continental crust (C) = 35 km

We need to convert all the above units from kilometers to miles:

E = \frac{0.6214 mi}{1 km}*6371 km = 3958.9 mi

O = \frac{0.6214 mi}{1 km}*7.5 km = 4.7 mi

C = \frac{0.6214 mi}{1 km}*35 km = 21.7 mi

Now, we can calculate the fraction of Earth's radius relative to each type of crust, with the given equation:

X = \frac{avg. \: thickness}{avg. \: radius} \times 100

  • <u>For the oceanic crust (O)</u>:

X = \frac{4.7 mi}{3958.9 mi}\times 100 = 0.12

  • <u>For the continental crust (C)</u>:

X = \frac{21.7 mi}{3958.9 mi}\times 100 = 0.55

Therefore, the fraction of Earth's radius relative to the oceanic and continental crust is 0.12 and 0.55, respectively.

You can see another example of calculation of fractions of Earth's radius here: brainly.com/question/4675868?referrer=searchResults

I hope it helps you!

6 0
2 years ago
Is. Fe(s) ---------------&gt; Fe2+(aq) + 2e−<br>oxidation or reduction?​
frez [133]

Answer:

Oxidation occurs at the anode: Fe(s) | Fe2+(aq) half cell. (ii) Reduction occurs at the cathode: Ag(s) | Ag+(aq) half cell. Oxidation occurs at the anode: Pt | Sn2+(aq), Sn4+(aq) half cell. (iii) Electrons flow from the anode to the cathode: from the Pt(s) → Ag(s) electrode.

4 0
2 years ago
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