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Brilliant_brown [7]
3 years ago
15

What is the percent of oxygen by mass in a pure sample of fecr2o4? 1. 52% 2. 13% 3. 37% 4. 7.1% 5. 29%?

Chemistry
1 answer:
Marta_Voda [28]3 years ago
6 0
Let us suppose that we have 1 mol of FeCr2O4. I'm going to use approximate masses because I have no idea what your periodic table will say. Just put in the exact masses from your periodic table.

Fe = 56
Cr*2 = 2*52 = 104
O4 = 4*16 = 64
===========
Total = 56 + 104 + 64 = 224
The % oxygen = (64 / 224) * 100 = 28.5 % but none of your answers match this. Perhaps you are talking about Fe2(Cr2O4)3 The brackets make all the difference in the world.

Without going through all the detail I did before, The molecular mass is
Fe * 2 = 112
Cr * 6 = 312
O * 12 = 192
The total molecular mass = 616

The % Oxygen = (192 / 616) * 100 = 31% roughly. That answer isn't there either. 

Let's wait and see who else answers.

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45.6 mL of 0.0600 M Ba(OH)2 is added to 25.0 mL of HCl of unknown concentration. What is the concentration of HCl?
Alex Ar [27]

45.6 mL of 0.0600 M of Ba(OH)_{2} is added to 25.0 mL of HCl of unknown concentration then , the  concentration of HCl is 0.032 M .

Calculation ,

Formula used : M_{1} V_{1} =  M_{2} V_{2}                 ...( 1 )

Where  M_{1}= concentration of Ba(OH)_{2}  =  0.0600 M ( given )

M_{2} = concentration of HCl = ? ( to be find )

 V_{1}= volume of Ba(OH)_{2}  = 25.0 mL  ( given )

V_{2} = volume of HCl = 45.6 mL  ( given )

Now , put the value of all volume and concentration in equation ( 1 ) we get .

0.0600 M ×  25.0 mL =  M_{2}  × 45.6 mL

M_{2}  =  0.0600 M ×  25.0 mL / 45.6 mL = 0.032 M

Therefore , concentration of  unknown concentration of HCl is 0.032 M .

to learn about concentration here ,

brainly.com/question/10725862

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7 0
1 year ago
calculate the speed of an electron if its de broglie wavelength is twice its displacement in one second
valkas [14]

Answer:

The speed of an electron is 0.01908 m/s.

Explanation:

De-Broglie wavelength is given by:

\lambda=\frac{h}{mv}

where,  \lambda = wavelength of a particle

h = Planck's constant = 6.626\times 10^{-34}Js

m = mass of particle

v = velocity of the particle

Velocity of an electron = v

Mass of an electron = 9.1\times 10^{-31}kg

Wavelength of electron is twice the displacement in seconds which is velocity of an electron.

Then.wavelength of an electron = \lambda =2v

\lambda =2v=\frac{6.626\times 10^{-34}Js}{9.1\times 10^{-31}kg\times v}

v = 0.01908 m/s

The speed of an electron is 0.01908 m/s.

5 0
3 years ago
A large highway barrier is 1 meter wide, by 1 meter tall, by 2 meters long.
Romashka [77]

Answer:

when mass is  1×10⁴ Kg then density is 5 g/cm³.

when mass is 104 Kg then density is 5.2 × 10⁻² g/ cm³.

Explanation:

Density:

Density is equal to the mass of substance divided by its volume.

Units:

SI unit of density is Kg/m3.

Other units are given below,

g/cm3, g/mL , kg/L

Formula:

D=m/v

D= density

m=mass

V=volume

Symbol:

The symbol used for density is called rho. It is represented by ρ. However letter D can also be used to represent the density.

Given data:

mass = 1×10⁴ Kg

volume= w ×l× h = 1×2× 1 = 2 m³

density = ?

first of all we will convert the given volume meter cube to cm³:

we know that  

2×1000000 = 2 × 10⁶ cm³

Now we will convert the mass into gram.

1 Kg = 1000 g

1×10⁴ × 1000 = 1 ×10⁷ g

Now we will put the values in the formula,

d = m/v

d = 1 ×10⁷ g / 2×10⁶ cm³

d = 0.5 × 10¹ g/cm³

   or

d = 5 g/cm³

If mas is 104 Kg:

104 × 1000 = 104000 g

d= m/v

d = 104000 g / 2×10⁶ cm³

d= 52000 ×10⁻⁶ g/ cm³

d= 5.2 × 10⁻² g/ cm³

7 0
3 years ago
7. How many grams are there in 2.5 moles of silver?
exis [7]
2.5 moles of silver is 269.6705 grams
4 0
3 years ago
Read 2 more answers
Assume that the pressure inside of the 1 liter balloon is 200,000 Pa, what is the explosive energy in the inside the balloon? Ex
AysviL [449]

Answer:

200 Joules is the explosive energy in the inside the balloon. And that is  9.523\times 10^{-5}1 lb of TNT.

Explanation:

Pressure=\frac{force}{Area}=\frac{Force\times distance}{Area \times distance}=\frac{Energy}{Volume}

Volume of the balloon = V = 1 L = 0.001 m^3

Pressure inside the balloon ,P= 200,000 Pa =200,000 N/m^2

Explosive energy in the inside the balloon be E.

E = Pressure × Volume

E=200,000 N/m^2\times 0.001 m^3=200 Joules

1 lb of TNT = 2.1\times 10^6 J

200 Joules = 200\times \frac{1}{2.1\times 10^6 }1 lb of TNT

= 9.523\times 10^{-5}1 lb of TNT

5 0
3 years ago
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