1answer.
Ask question
Login Signup
Ask question
All categories
  • English
  • Mathematics
  • Social Studies
  • Business
  • History
  • Health
  • Geography
  • Biology
  • Physics
  • Chemistry
  • Computers and Technology
  • Arts
  • World Languages
  • Spanish
  • French
  • German
  • Advanced Placement (AP)
  • SAT
  • Medicine
  • Law
  • Engineering
kupik [55]
3 years ago
9

Magnetite is a binary compound containing only iron and oxygen. the percent, by weight, of iron is 72.360%. what is the empirica

l formula of magnetite?
a. feo
b. fe2o3
c. fe3o4
d. feo2
Chemistry
2 answers:
hram777 [196]3 years ago
7 0
Answer is: <span>c. Fe</span>₃<span>O</span>₄<span>.
</span>ω(Fe) = 72,360%.
ω(O) = 100% - 72,36% = 27,64%.
For example, if we the mass of compound is 100 g:
m(Fe) = 72,36 g.
n(Fe) = m(Fe) ÷ M(Fe).
n(Fe) = 72,36 g ÷ 55,85 g/mol.
n(Fe) = 1,296 mol.
n(O) = 27,64 g ÷ 16 g/mol.
n(O) = 1,727 mol.
n(Fe) : n(O) = 1,296 mol : 1,727 mol.
n(Fe) : n(O) = 1 : 1,33 or 3 : 4.
Arturiano [62]3 years ago
7 0
<span>Option C. The percentages can be taken for mass. So mass of Iron = 72.360% = 72.36g So mass of Oxygen = 100 - 72.360 = 27.694% = 27.65g Number of moles of Iron = mass/ molar mass = 72.36/ 55.854 = 1.29 Number of moles of Oxygen = 27.65/16 = 1 .728 We shall divide by the smallest So we have 1.29/1.29 = 1 while 1.728/1.29 = 1.33 But 1.33 = 4/3. So we multiply by the lowest common number which happens to be a 3. Hence the empirical formula is Fe3O4.</span>
You might be interested in
Which is the correct Lewis dot structure of NH2?<br><br> A.A<br> B.B<br> C.C<br> D.D<br> E.E
Anarel [89]

I think D is your answer

5 0
3 years ago
Read 2 more answers
Pls complete the table with the correct answer ​
nalin [4]

Answer:

The correct answer is :

Natural fibres: these fibers are found naturally in the environment such as cotton, hemp or wool, all are made naturally found fibers.

sr. no.      name              type

1 Cotton natural

2 Linen natural

3 Silk natural

4 Wool natural

    5.     Hemp                natural

Artificial fibres: made from the polymerization of their monomer unit for example polyester made from coal and petroleum products.

sr. no.      name              type

1 Polyester artificial

2 Rayon artificial

3 Spandex artificial

4 Acrylic artificial

    5.     microfibers         artificial

6 0
4 years ago
Sound travels most quickly through solids because _____. solids have greater frequencies the molecules in solids are very close
uranmaximum [27]
Sound travels most quickly through solids because _____.

answer is: because solids r the most sense.

The distance between molecules in solids r very small.Because they are so close, they can collide very quickly, i.e. it takes less time for a molecule of the solid to 'bump' into its neighbor. Solids are packed together tighter than liquids and gases, hence sound travels fastest in solids.

7 0
3 years ago
Read 2 more answers
5. Write a net ionic equation that occurs in a Na2HPO4/NaH2PO4 buffer solution when: A) a small amount of HCl is added (2 points
labwork [276]

Answer: (A) H_{3}O^{+}(aq) + HPO^{2-}_{4}(aq) \rightarrow H_{2}PO^{2-}_{4}(aq) + H_{2}O(l)

(B) H_{2}PO^{-}_{4}(aq) + OH^{-}(aq) \rightarrow HPO^{2-}_{4}(aq) + H_{2}O(l)

Explanation:

(A) As we know that HCl is a strong acid and when it is added to an aqueous solution then it leads to increase in the concentration of hydrogen ions. And, when an acid or base is added to a solution then any resistance by the solution in changing the pH of the solution is known as a buffer.

This means that addition of buffer into the given solution will not cause much change in the concentration of H_{3}O^{+} in large amount.

As both the buffer components are salt then they will remain dissociated as follows.

       Na_{2}HPO_{4}(aq) \rightarrow 2Na^{+}(aq) + HPO^{2-}_{4}(aq)

 NaH_{2}PO_{4}(aq) \rightarrow Na^{+}(aq) + H_{2}PO^{-}_{4}(aq)

Hence, net ionic equation will be as follows.

       H_{3}O^{+}(aq) + HPO^{2-}_{4}(aq) \rightarrow H_{2}PO^{2-}_{4}(aq) + H_{2}O(l)

(B)  When we add small amount of sodium hydroxide into the solution then there will occur an increase in concentration of hydroxide ions into the solution. But then due to the presence of buffer there will occur not much change in concentration and the acid will get converted into salt.

     NaOH(aq) \rightarrow Na^{+}(aq) + OH^{-}(aq)

The net ionic equation is as follows.

        H_{2}PO^{-}_{4}(aq) + OH^{-}(aq) \rightarrow HPO^{2-}_{4}(aq) + H_{2}O(l)

7 0
3 years ago
Phosphoric acid (h3po4) is tribasic, with pka's of 2.14, 6.86, and 12.4. The charge of the ionic form that predominates at ph 3.
Annette [7]

Correct answer is H_2PO_4^-.

Phosphoric acid is a polyprotic acid having 3 acidic hyrdogen therefore it will have 3 pka values.

The equations for the release of acidic hydrogen can be written as:

\\H_3PO_4\rightleftharpoons H_2PO_4^-+H^+\text{ pka=2.14}\\H_2PO_4^-\rightleftharpoons HPO_4^2^-+H^+\text{ pka=6.86}\\HPO_4^2^-\rightleftharpoons PO_4^3^-+H^+\text{ pka=12.4}

From the pka values we can judge the idea of pH as using Henderson-Hasselbalch Equation, we get the relation between pH and pka.

HA\rightarrow H^-+A^-

Using the following equation, relation of pH and pka is

pH=pka+log\frac{[A^-]}{HA}

Using this equation, we can find that the equation having pka= 2. 14 is closest to the pH=3.2 so the ionic form in this equation will be dominant at the same pH.

Therefore at pH=3.2 the ionic form H_2PO_4^- of H_3PO_4 is dominant.


7 0
3 years ago
Read 2 more answers
Other questions:
  • What are the spectator ions in 2H+ + SO42- + Ca2+ + 21 → CaSO4 + 2H+ + 21-?
    12·2 answers
  • Calculate the mass of water produced when 3.03 g of butane reacts with excess oxygen.
    14·1 answer
  • How much energy does a 9 x 10^8m wavelength photon have?
    12·1 answer
  • Which characteristic best identifies a decomposition reaction?
    10·1 answer
  • A student makes measurements to calculate the density of a rod of aluminum to be
    14·1 answer
  • It has been suggested that the surface melting of ice plays a role in enabling speed skaters to achieve peak performance. Carry
    15·1 answer
  • A pre-1964 quarter, made
    5·1 answer
  • Select the correct balanced equation for the combustion of methane.<br> CH4 + 02 -&gt; CO 2 + H2O
    14·1 answer
  • 1)Given the following thermochemical equations
    12·1 answer
  • A flask contains a 1.00 mole of neon gas and 2.00 moles of argon gas. If the total pressure of the gases is 150.0 kPa, then what
    7·1 answer
Add answer
Login
Not registered? Fast signup
Signup
Login Signup
Ask question!