4Fe + 3O2  2Fe2O3

Which of these is an example of how engineers have affected society?

Levart [38]

You can eliminate A, C, and D almost instantly if you know that engineers are construction workers. The answer is B.

8 0

3 years ago

A solution is made by dissolving 4.87 g of potassium nitrate in water to a final volume of 86.4 mL solution. What is the weight/

lara31 [8.8K]

Answer:

A solution is made by dissolving 4.87 g of potassium nitrate in water to a final volume of 86.4 mL solution. The weight/weight % or percent by mass of the solute is :

2.67%

Explanation:

Note : Look at the density of potassium nitrate in water if given in the question.

You are calculating weight /Volume not weight/weight % or percent by mass of the solute

Here the weight/weight % or percent by mass of the solute is asked : So first convert the VOLUME OF SOLUTION into MASS

Density of potassium nitrate in water KNO3 = 2.11 g/mL

$density=\frac{mass}{volume}$

Density = 2.11 g/mL

Volume of solution = 86.4 mL

$2.11=\frac{mass}{86.4}$

$mass = 2.11\times 86.4$

$mass=182.3grams$

Mass of Solute = 4.87 g

Mass of Solution = 183.2 g

w/w% of the solute =

$= \frac{mass\ of\ solute}{mass\ of\ solution}\times 100$

$=\frac{4.87}{183.2}\times 100$

w/w%=2.67%

8 0

3 years ago

Calculate the mass of Cr(ClO2)2 that contains 5.57 × 10 ^22 chlorine atoms.

Anna007 [38]

Answer:

Explanation:

Your strategy here will be to

use the chemical formula of carbon dioxide to find the number of molecules of

CO

2

that would contain that many atoms of oxygen

use Avogadro's constant to convert the number of molecules to moles of carbon dioxide

use the molar mass of carbon dioxide to convert the moles to grams

So, you know that one molecule of carbon dioxide contains

one atom of carbon,

1

×

C

two atoms of oxygen,

2

×

O

This means that the given number of atoms of oxygen would correspond to

4.8

⋅

10

22

atoms O

⋅

1 molecule CO

2

atoms O

=

2.4

⋅

10

22

molecules CO

2

Now, one mole of any molecular substance contains exactly

6.022

⋅

10

22

molecules of that substance -- this is known as Avogadro's constant.

In your case, the sample of carbon dioxide molecules contains

2.4

⋅

10

22

molecules CO

2

⋅

1 mole CO

2

6.022

⋅

10

23

molecules CO

2

=

0.03985 moles CO

2

Finally, carbon dioxide has a molar mass of

44.01 g mol

−

1

, which means that your sample will have a mass of

0.03985

moles CO

2

⋅

44.01 g

1

mole CO

2

=

¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯

∣

a

1.8 g

a

∣

−−−−−−−−−

The answer is rounded to two sig figs, the number of sig figs you have for the number of atoms of oxygen present in the sample.

3 0

2 years ago

The best solution to the solid waste problem is to ________. the best solution to the solid waste problem is to ________. increa

yaroslaw [1]

the answer is decade and waste

8 0

3 years ago

8. If I have 34 grams of FeO, how many grams of Oxygen were synthesized? Fe + O2 → Feo

krek1111 [17]

Answer:

34 gram of FeO produced 8 gram of oxygen.

Explanation:

Given data:

Mass of FeO = 34 g

Mass of oxygen = ?

Solution;

Chemical equation:

2FeO → 2Fe + O₂

Number of moles of FeO:

Number of moles = mass/ molar mass

Number of moles = 34 g /71.8 g/mol

Number of moles = 0.5 mol

Now we will compare the moles of FeO with oxygen:

FeO : O₂

2 : 1

0.5 : 1/2 × 0.5 = 0.25

Mass of oxygen:

Mass = number of moles × molar mass

Mass = 0.25 mol × 32 g/mol

Mass = 8 g

So 34 gram of FeO produced 8 gram of oxygen.

8 0

3 years ago