How many moles of water are formed from 0.65 moles of oxygen?

A chemist needs 10 liters of a 25% acid solution. The solution is to be mixed from three solutions whose concentrations are 10%,

mojhsa [17]

Answer:

a) 1 litre of 10% solution and 7 litre of 20% solution

b) 1.67 litres of 50% solution and 8.33 litres of the 20% solution

c) 3.75 litres of 50% solution and 6.25 litres of 20% solution

Explanation:

Given:

chemist needs = 10 liters of a 25% acid solution

Concentration of three solutions that are to be mixed = 10%, 20% and 50%.

Solution:

A) Use 2 liters of the 50% solution

Let us mix this with 10% and 20% solution

They will have to equal 8 litres

Let x=20% solution

Then (8-x) =10%

So the equation becomes,

10%(8-x)+ 20%x+50%(2)=25(10)

(0.1)(8-x) +0.2x+0.50(2)= 0.25(10)

0.8-0.1x+0.2x+1.0=2.5

0.2x-0.1x=2.5-0.8-1.0

0.1x=0.7

$x=\frac{0.7}{0.1}$

x= 7

so, 8-x = 8 -7= 1 litre of 10% solution and 7 litre of 20% solution

B)Use as little as possible of the 50% solution

Let x be the amount of 50% solution.

Then(10-x) be the 20% solution

Now the equation becomes,

50%(x)+20%(10-x)=25%(10)

0.50x+0.2(10-x)=0.25(10)

0.5x+2.0-0.2x=2.5

0.3x=2.5-2.0

0.3x=0.5

$x=\frac{0.5}{0.3}$

x=1.67

now (10-x)=(10-1.67)=8.33

so there will be 1.67 litres of 50% solution and 8.33 litres of the 20% solution

c) ) Use as much as possible of the 50% solution

Let x be the amount of 50% solution.

Then(10-x) be the 20% solution

Now the equation becomes,

50%(x)+10%(10-x)=25%(10)

0.50x+0.1(10-x)=0.25(10)

0.5x+1.0-0.1x=2.5

0.4x=2.5-1.0

0.4x=1.5

$x=\frac{1.5}{0.3}$

x=3.75

Now, (10-x)=(10- 3.75)=6.26

So there will be 3.75 litres of 50% solution and 6.25 litres of 20% solution

5 0

3 years ago

If a covalent bond consists of a hydrogen atom and an oxygen atom, which atom will have a partial negative charge (-)? Which at

Oxana [17]

Answer: The Oxygen will have a partial negative charge, and the hydrogen will have a partial positive charge.

Explanation:

Electronegativity is the tendency of an atom to attract a pair of electrons when forming a chemical bond. The more electronegative atom will attract the electrons more, and will have a partial negative charge, because the electrons are negatively charged. The less electronegative atom will have the electrons the other atom attracted further away from it, so it will have a partial positive charge.

Oxygen is more electronegative than hydrogen. Oxygen has a nuclear charge of 16 protons (positively charged), whereas hydrogen only has 1. As a result, the pull these 16 protons produce on the electrons will be stronger than the pull only 1 proton produces, and the electrons will be closer to the Oxygen atom.

6 0

4 years ago

How do experiments help scientists learn about the world?

arsen [322]

Answer:

A. Experiment help explain scientific theories

7 0

3 years ago

cherries on a tree freeze at -2°. The weather forecast said that tonight's low is -5° C. The old farmer sprays down his trees wi

just olya [345]

Old wives tale

Explanation:

This is an old wives tale and not scientifically correct.

Water is liquid that is known to freeze at 0° C.

The boiling point of water is also 100° C.

If the farmer sprays the cherries on the tree with water, it suggests that they will freeze faster because water has high freezing point compared to that of the cherry.
This will not in any way protect the cherries on the tree.
To prevent the cherries from freezing, he should spray them with something that has lower freezing point.

learn more:

Freezing point brainly.com/question/11126965

#learnwithBrainly

4 0

4 years ago

In which of the following is the number of electrons the ion contains given correctly

larisa [96]

Answer:

B. K+ has 18 electrons

Explanation:

Ions are formed when atoms of element gain or loose electrons.
When an atom looses electrons it forms a positively charged ion and when an atom gains electrons it forms a negatively charged ion.
Metal atoms such as potassium, magnesium and aluminium looses outer most electrons to positively charged ions.
Potassium atom has 19 electrons, 19 protons, with an electronic configuration of 2 : 8 : 8 : 1. To form an ion, K looses an electron to form a positively charged potassium ion (K+) with 18 electrons and 19 protons and an electronic configuration of 2:8:8.

8 0

3 years ago