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3 years ago

When do scientists use models i will mark best one brainlest

2 answers:

4 0

They use models when they are trying to find stuff in the ground like fossils so they match them up so they can find if it’s the same or not please mark brainliest must appreciated !

aliina [53]3 years ago

3 0

Scientists use models when doing research to lay out their data. They can also use them to explore phenomena that are too vast complex or to dangerous to study first hand. They use it to investigate objects or processes that happen too slowly to quickly or on to small of a scale to observe directly

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A solution contains 0.140 mol KCl in 2.100 L water. What is the concentration of KCl in g/L?

viva [34]

<h3>Answer;</h3>

≈ 4.95 g/L

<h3>Explanation;</h3>

The molar mass of KCl = 74.5 g/mole

Therefore; 0.140 moles will be equivalent to ;

= 0.140 moles × 74.5 g/mole

= 10.43 g

Concentration in g/L

= mass in g/volume in L

= 10.43/2.1

= 4.9667

4 0

3 years ago

Calculate the percent ionization of formic acid (hco2h) in a solution that is 0.311 m in formic acid and 0.189 m in sodium forma

ohaa [14]

Answer: 0.094%

Explanation:


1) Equilibrium chemical equation:


Only the ionization of the formic acid is the important part.


HCOOH(aq) ⇄ HCOO⁻(aq) + H⁺(aq).


2) Mass balance:


 HCOOH(aq) HCOO⁻(aq) H⁺(aq).

Start 0.311 0.189

Reaction - x +x +x

Final 0.311 - x 0.189 + x x

3) Acid constant equation:


Ka = [HCOO-] [N+] / [HCOOH] = (0.189 + x) x / (0.311 -x)


= (0.189 + x )x / (0.311 - x) = 0.000177

4) Solve the equation:

You can solve it exactly (it will lead to a quadratic equation so you can use the quadratiic formula). I suggest to use the fact that x is much much smaller than 0.189 and 0.311.


With that approximation the equation to solve becomes:

0.1890x / 0.311 = 0.000177, which leads to:

x = 0.000177 x 0.311 / 0.189 = 2.91 x 10⁻⁴ M

5) With that number, the percent of ionization (alfa) is:


percent of ionization = (moles ionized / initial moles) x 100 =


percent ionization = (concentration of ions / initial concentration) x 100 =


percent ionization = (0.000291 / 0.311)x 100 = 0.0936% = 0.094%

8 0

3 years ago

In a common experiment in the general chemistry laboratory, magnesium metal is heated in air to produce MgO. MgO is a white soli

Digiron [165]

Explanation:

When magnesium metal burns is heated i the air it forms magnesium oxide.The balanced chemical reaction is given as:

$2Mg+O_2\rightarrow 2MgO$

2 moles of magnesium metal when reacts with 1 moles of oxygen it gives 2 moles of magnesium oxide which is white in color.

Some times along with formation of magnesium oxide small amount of magnesium nitride also produced due to which magnesium oxide appears grey in color .The balanced chemical reaction is given as:

$3Mg+N_2\rightarrow Mg_3N_2$

3 moles of magnesium combines with 1 mol of nitrogen gas to to give 1 mol of magnesium nitride.

6 0

3 years ago

TRUE or FALSE

andriy [413]

Answer:

1. true

2. false

3. true

Explanation:

5 0

2 years ago

What is protons most common ion

melisa1 [442]

Hydrogen ion, strictly, the nucleus of a hydrogen atom separated from its accompanying electron. The hydrogen nucleus is made up of a particle carrying a unit positive electric charge, called a proton. The isolated hydrogen ion, represented by the symbol H +, is therefore customarily used to represent a proton.

3 0

3 years ago