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4 years ago

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Aluminum oxide was prepared by heating 225 g of chromium (III) oxide with 125 g of aluminum. Calculate the percent yield of 100.

0 g of aluminum oxide were obtained

1 answer:

Veronika [31]4 years ago

4 0

Answer:

66.25%

Explanation:

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Find the density of an 8 gram rock if the water in a graduated cylinder rises from 25.0 mL to

Olin [163]

To measure the density of the stone placed in a graduated cylinder let us follow these steps bellow

Measure the volume of water poured into a graduated cylinder
Place the object in the water and remeasure the volume.
The difference between the two volume measurements is the volume of the object.
Divide the mass by the volume to calculate the density of the object.

<em>We know that the formula for density is given as </em>

Given data

Mass = 8gram

Initial Volume of water in cylinder = 25mL

Final Volume of water in cylinder = 29mL

Hence the volume of the rock = 29-25 = 4mL

Therefore the density of the rock = 8/4 = 2 g/mL

Learn more:

brainly.com/question/17336041

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2 years ago

what mass of sodium fluoride (FW=42.0 g/mol) must be added to 3.50 x 10^2 mL of water to give a solution with pH = 8.40?

MaRussiya [10]

Answer:

Explanation:

Sodium fluoride, being a salt, dissolves in water completely producing F ⁻ ions. Now F⁻ is the conjugate base of the weak acid HF, so in water we will have the following equilibrium:

F⁻ + H₂O ⇆ HF + OH⁻

Given this equilibrium, we need to calculate Kb from the Ka for HF, the [ OH ⁻] from the given pH, and finally the mass needed to produce that OH⁻ concentration.

The equilibrium constant, Kb , can be calculated from Kw = Ka x Kb, where Kw = 10⁻¹⁴ and Ka for HF is 6.6 x 10⁻⁴ from reference tables.

Kb = 10⁻¹⁴ / 6.6 x 10⁻⁴ = 1.5 x 10⁻¹¹

pH + pOH = 14 ⇒ pOH = 14 - 8.40 = 5.60

[ OH⁻ ] = 10^-5.60 = 2.51 x 10⁻⁶

Now we have all the information :

F⁻ HF OH⁻

Equilibrium X 2.51 x 10⁻⁶ 2.51 x 10⁻⁶

(2.51 x 10⁻⁶)² / X = 1.5 x 10⁻¹¹ ⇒ X = (2.51 x 10⁻⁶)² / 1.5 x 10⁻¹¹

X = [ F⁻ ] = 0.41 M

For 350 mL ( 0.35 L ) we need to add:

0.41 mol HF/ 1 L * 0.35 L = 0.144 mol

and finally the mass will be:

0.144 mol NaF * 42.0 g/mol NaF = 6.03 g NaF

7 0

3 years ago

For the reaction represented by the equation  2Fe + O2 → 2FeO, how many moles of iron oxide will be produced from 8.00 mol of ir

STatiana [176]

Answer:

8.00 moles.

Explanation:

The ratio of Fe to FeO is 2:2 = 1:1, so 8 moles are produced.

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3 years ago

a boulder of shore is slowly broken apart by the force of the water it is a change or it is a example

natima [27]

Answer:

I think that this would be an example of erosion

6 0

2 years ago

A cylinder with a movable piston originally has a volume of 2805 mL and is filled with nitrogen to a pressure of 4.00

Sergio039 [100]

This problem is providing the initial volume and pressure of nitrogen in a piston-cylinder system and asks for the final pressure it will have when the volume increases. At the end, the answer turns out to be 2.90 atm.

<h3>Boyle's law</h3>

In chemistry, gas laws are used so as to understand the volume-pressure-temperature-moles behavior in ideal gases and relate different pairs of variables.

In this case, we focus on the Boyle's law as an inversely proportional relationship between both pressure and volume at constant both temperature and moles:

$P_1V_1=P_2V_2$

Thus, we solve for the final pressure by dividing both sides by V2:

$P_2=\frac{P_1V_1}{V_2}$

Hence, we plug in both the initial pressure and volume and final volume in order to calculate the final pressure:

$P_2=\frac{2805mL*4.00atm}{3864mL}\\ \\P_2=2.90atm$

Learn more about ideal gases: brainly.com/question/8711877

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3 years ago