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sukhopar [10]
3 years ago
7

The person writes a coefficient of 2 in front of Fe2O3 but then writes a 4 for the number of iron (Fe) atoms. Explain this diffe

rence.
Chemistry
2 answers:
den301095 [7]3 years ago
6 0

Answer:

See explanation

Explanation:

Given that the formula of the compound is Fe2O3, if a coefficient of 2 is placed in front of the formula, that is, if we write 2Fe2O3 . Then;

The number of Fe atoms becomes 2 *2 = 4

The number of oxygen atoms becomes 2*3 = 6

That is why the total number of iron atoms were written down as 4.

Inessa [10]3 years ago
6 0

Answer:

The person writes a coefficient of 2 in front of Fe2O3 but then writes a 4 for the number of iron (Fe) atoms. Explain this difference.

Explanatio:

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Calculate the number of calories needed to increase the temperature of 50.0 g of copper metal from 21.0 degrees C to 75.0 degree
KonstantinChe [14]
<h3>Answer:</h3>

1031.4 Calories.

<h3>Explanation:</h3>

We are given;

Mass of the copper metal = 50.0 g

Initial temperature = 21.0 °C

Final temperature, = 75°C

Change in temperature = 54°C

Specific heat capacity of copper = 0.382 Cal/g°C

We are required to calculate the amount of heat in calories required to raise the temperature of the copper metal;

Quantity of heat is given by the formula,

Q = Mass × specific heat capacity × change in temperature

   = 50.0 g × 0.382 Cal/g°C × 54 °C

   = 1031.4 Calories

Thus, the amount of heat energy required is 1031.4 Calories.

4 0
3 years ago
A chemist titrates 150.0 mL of a 0.2653 M carbonic acid (H2CO3) solution with 0.2196 M NaOH solution at 25 °C. Calculate the pH
xxTIMURxx [149]

Answer:

9.3

Explanation:

This is long and complicated so get ready

We are going to use the conjugate base of carbonic acid with water to make carbonic acid and OH- (Na is simply a spectator ion and is irrelavent here)

Let the conjugate base be A- and Carbonic acid be HA

A- + H20 ⇄ HA + OH-

To find the concentration of A- we must find the concentration of the reactants given. We know this will be equal because it is a strong base and all of it disassociates.

to get moles of acid we take the concentration and multiply by liters to cancel

.2653 x .150 = .039795 mol HA

Because it is at equivalence point we know the moles will be equal. We are given the concentration so we only have to solve for liters

We plug it into the equation and found: .181 L

Now use moles and combined volums to fins concentrarion which is .120 M

Now plug that use the Ka converted to Kb to find the cincentrations of HA and OH-

Ka is (10^-3.60) = 2.4E-4

Kb x Ka is 10^-14

Kb = 3.98E-11

Now we know Kb = [HA] [OH] / [A-]

Solve for this through algebra by using x for the values you dont know

youll find x^2 = 3.3E-10

X = 1.8 E -5

this is the OH- concentration

-log [oh] = pOH

pOH = 4.73

We know 14-pOH = ph so pH= 9.3

6 0
3 years ago
Name the four elements on the Periodic Table that are considered METALLOIDS?​
Nimfa-mama [501]

Answer:

boron (B), silicon (Si), germanium (Ge), arsenic (As), antimony (Sb), tellurium (Te), polonium (Po) and astatine (At)

Explanation:

metalloids are elements that are in between the metals and nonmetals. they are in between because they have properties of both metals and nonmetals.

you can search "metalloids on the periodic table" and go to images to see what i mean :)

5 0
3 years ago
g If 50.0 mL of a 0.75 M acetic acid solution is titrated with 1.0 M sodium hydroxide, what is the pH after 10.0 mL of NaOH have
V125BC [204]

Answer:

pH = 2.66

Explanation:

  • Acetic Acid + NaOH → Sodium Acetate + H₂O

First we <u>calculate the number of moles of each reactant</u>, using the <em>given volumes and concentrations</em>:

  • 0.75 M Acetic acid * 50.0 mL = 37.5 mmol acetic acid
  • 1.0 M NaOH * 10.0 mL = 10 mmol NaOH

We<u> calculate how many acetic acid moles remain after the reaction</u>:

  • 37.5 mmol - 10 mmol = 27.5 mmol acetic acid

We now <u>calculate the molar concentration of acetic acid after the reaction</u>:

27.5 mmol / (50.0 mL + 10.0 mL) = 0.458 M

Then we <u>calculate [H⁺]</u>, using the<em> following formula for weak acid solutions</em>:

  • [H⁺] = \sqrt{C*Ka}=\sqrt{0.458M*1.76x10^{-5}}
  • [H⁺] = 0.0028

Finally we <u>calculate the pH</u>:

  • pH = -log[H⁺]
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8 0
3 years ago
An industrial chemist is studying a sample of an unknown metal. Describe two ways he could change the metal physically and two w
Trava [24]

Answer:

Some of the physical changes used by the industrial chemist in order to identify it is by scratching it with other metals in order to find the hardness of it. Trying to deform it in order to find the malleability, and to heat it and measure the temperature in order to find the melting point.  

Some of the chemical changes used by the industrial chemist in order to identify it is by inserting it in water to observe that whether it reacts with it or not, if the reaction is violent, then the metal belongs to either group I or group II. The other method is to insert it in acids of distinct strength and to observe its reaction. The metals belonging to the second group react briskly with acids. The other metals react gradually with acids and others are almost inert.  

3 0
3 years ago
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