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2 years ago

2Fe + 6HCl -> 2FeCl3 + 3H2 If 7.0 moles of HCl is added to enough iron that the HCl is completely used up, how many

Chemistry

1 answer:

DENIUS [597]2 years ago

3 0

Answer: 3.5 moles of hydrogen gas will be produced.

Explanation:

The balanced chemical equation is:

$2Fe+6HCl\rightarrow 2FeCl_3+3H_2$

As HCl gets completely used up, $HCl$ is the limiting reagent.

According to stoichiometry :

6 moles of $HCl$ produces = 3 moles of $H_2$

Thus 7.0 moles of $HCl$ produces= $\frac{3}{6}\times 7.0=3.5moles$ of $H_2$

Thus 3.5 moles of hydrogen gas will be produced.

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Recovery standards are a necessary tool for determining exactly how much of a particular analyte you are able to extract from a

Dafna11 [192]

Answer:

2.05mg Fe/ g sample

Explanation:

In all chemical extractions you lose analyte. Recovery standards are a way to know how many analyte you lose.

In the problem you recover 3.5mg Fe / 1.0101g sample: 3.465mg Fe / g sample. As real concentration of the standard is 4.0 mg / g of sample the percent of recovery extraction is:

3.465 / 4×100 = 86,6%

As the recovery of your sample was 1.7mg Fe / 0.9582g, the Iron present in your sample is:

1.7mg Fe / 0.9582g sample× (100/86.6) = 2.05mg Fe / g sample

I hope it helps!

5 0

3 years ago

Picric acid has been used in the leather industry and in etching copper. However, its laboratory use has been restricted because

olchik [2.2K]

Answer:

0.3023 M

Explanation:

Let Picric acid = $H_{picric}$

So, $H_{picric}$ + $H_2}O$ ⇄ $H_3}O^+$ + $Picric^-$

The ICE table can be given as:

$H_{picric}$ + $H_2}O$ ⇄ $H_3}O^+$ + $Picric^-$

Initial: 0.52 0 0

Change: - x + x + x

Equilibrium: 0.52 - x + x + x

Given that;

acid dissociation constant ( $K_a$ ) = 0.42

$K_a = \frac{[H_3O^+][Picric^-]}{H_{picric}}$

$0.42 = \frac{[x][x]}{0.52-x}}$

$0.42 = \frac{[x]^2}{0.52-x}}$

0.42(0.52-x) = x²

0.2184 - 0.42x = x²

x² + 0.42x - 0.2184 = 0 -------------------- (quadratic equation)

Using the quadratic formula;

$\frac{-b+/-\sqrt{b^2-4ac} }{2a}$ ; ( where +/- represent ± )

= $\frac{-0.42+/-\sqrt{(0.42)^2-4(1)(-0.2184)} }{2*1}$

= $\frac{-0.42+/-\sqrt {0.1764+0.8736} }{2}$

= $\frac{-0.42+\sqrt {1.0496} }{2}$ OR $\frac{-0.42-\sqrt {1.0496} }{2}$

= $\frac{-0.42+1.0245}{2}$ OR $\frac{-0.42-1.0245}{2}$

= $\frac{0.6045}{2}$ OR $-\frac{1.4445}{2}$

= 0.30225 OR - 0.72225

So, we go by the +ve integer that says:

x = 0.30225

x = [ $H_3}O^+$ ] = [ $Picric^-$ ] = 0.3023 M

∴ the value of [H3O+] for an 0.52 M solution of picric acid = 0.3023 M (to 4 decimal places).

6 0

3 years ago

When two clear, colourless liquids are mixed together, a yellow precipitate is formed. This is an example of a

Flura [38]

Answer:

Combining the two clear colorless liquids is a chemical change.

Explanation:

Because a different solid substance is formed. Tell students that a precipitate is an insoluble solid that forms when two solutions are combined and react chemically. Insoluble means that the solid will not dissolve.

3 0

3 years ago

What is the sum of the coefficients of the balanced equation for:

Marianna [84]

Answer:

3 Pb(NO3)2 + Al2(SO4)3 = 2 Al(NO3)3 + 3 PbSO4

Explanation:

I think your equation is incorrect? This is balanced and the sum of coefficients is 9.

5 0

2 years ago

What are the parts of the earths mantle? A) Inner core, asthensophere, lithosphere

In-s [12.5K]

Answer:

Explanation:

The mantle is composed of the mesosphere and the asthenosphere in the upper most part and in the crust is the lithosphere

5 0

2 years ago