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3 years ago

How do you think the atomic radii will change as electrons are added to a shell?

2 answers:

6 0

As electrons are added to the valence shell, an extra proton (i.e fundamental, positively charged nuclear particle) is added to the element's nucleus. As electrons add and Z the atomic number increases 1 by 1, nuclear charge WINS, and electronic radii contract.

kirill115 [55]3 years ago

3 0

Answer:

Explanation:

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4. Find the pH at each of the following points in the titration of 25 mL of 0.3 M HF with 0.3 M NaOH. The Ka value is 6.6x10-4 a

yawa3891 [41]

Explanation:

Since HF is a weak acid, the use of an ICE table is required to find the pH. The question gives us the concentration of the HF.

HF+H2O⇌H3O++F−HF+H2O⇌H3O++F−

Initial0.3 M-0 M0 MChange- X-+ X+XEquilibrium0.3 - X-X MX M

Writing the information from the ICE Table in Equation form yields

6.6×10−4=x20.3−x6.6×10−4=x20.3−x

Manipulating the equation to get everything on one side yields

0=x2+6.6×10−4x−1.98×10−40=x2+6.6×10−4x−1.98×10−4

Now this information is plugged into the quadratic formula to give

x=−6.6×10−4±(6.6×10−4)2−4(1)(−1.98×10−4)−−−−−−−−−−−−−−−−−−−−−−−−−−−−√2x=−6.6×10−4±(6.6×10−4)2−4(1)(−1.98×10−4)2

The quadratic formula yields that x=0.013745 and x=-0.014405

However we can rule out x=-0.014405 because there cannot be negative concentrations. Therefore to get the pH we plug the concentration of H3O+ into the equation pH=-log(0.013745) and get pH=1.86

6 0

2 years ago

Calculate the ph of a solution formed by mixing 200.0 ml of 0.30 m hclo with 300.0 ml of 0.20 m kclo. the ka for hclo is 2.9 × 1

masha68 [24]

Answer:

The pH of the solution will be 7.53.

Explanation:

Dissociation constant of KClO= $K_a=2.8\times 10^{-8}$

Concentration of acid in 1 l= 0.30 M

Then in 200 ml = $0.30 M\times 0.200 L=0.06 M$

The concentration of acid, HClO=[acid]= 0.006 M

Concentration of salt in 1 L = 0.20 M

Then in 300 ml = $0.20 M\times 0.300 L=0.06 M$

The concentration of acid, KClO=[salt]= 0.006 M

The pH of the solution will be given by formula :

$pH=pK_{a}^o+\log\frac{[salt]}{[acid]}$

$pH=-\log[2.8\times 10^{-8}]+\frac{[0.06 M]}{[0.06 M]}$

The pH of the solution will be 7.53.

4 0

3 years ago

Read 2 more answers

In the lab you measure a clean dry crucible and cover to be 24.36 grams. You obtain a 2cm piece of pure magnesium metal. After s

mart [117]

Answer:

1) 0.3g Mg

2)0.5g MgO

3)0.2g O

4)0.01mol Mg & 0.01mol O

5)0.01mol MgO

6) Empirical formula MgO

Explanation:

The mass og Mg is obtained by substracting 24.36g from 24.66g:

24.66 - 24.36 = 0.3g Mg

The ignition of Mg means that it's reacting with oxygen to form an oxide. The increase in the crucible mass after the Mg ignition is due to the addition of oxygen. However, the addition of few drops of water produces a new compound: a hydroxide. According to the oxidation state og Mg (2+), the only magnesium oxide possible is MgO. It happens because the oxidation state of oxygen in oxides is 2-. Which means that just one oxygen atom is required to electrically neutralize one magnesium atom.

We can use a conversion factor to know how much MgO is made from from 0.3 g of Mg:

$0.3g Mg$ * $\frac{16gO}{24.3gMg}$ = 0.2g O

Thereby the mass of the oxide is 0.2g O + 0.3g Mg = 0.5g MgO

We convert the mass of oxygen and magnesium to the respective amounts in moles by using conversion factors:

$0.2g O$ * $\frac{1 mol O}{16g O}$ = 0.01mol O

$0.3g Mg$ * $\frac{1mol Mg}{24.3g Mg}$ = 0.01mol Mg

The moles of MgO can be obtained from:

$0.5g MgO$ * $\frac{1mol MgO}{40.3g MgO}$ = 0.01mol MgO

To obtain the empirical formula, the amount fo moles of each elements must be divided by the smallest one, in this case, 0.01.

The result for both number of Mg atoms and O atoms is 1. This can be interpreted to mean that there is a Mg atom for each O atom forming the formula unit of the compound.

The step when water is added to the compound resulting after heating does not affect the calculations necessary for the magnesium oxide.

4 0

2 years ago

Approximately how much of the world’s oil and natural gas reserves are believed to be in the arctic? View Available Hint(s) Appr

Gnoma [55]

Answer:

1/4 or 25%

Explanation:

The Arctic region of the earth refers to that part of the earth around the north pole region. Hence, when we are talking about latitude O degrees North, the areas around this geographical location is referred to as the arctic.

Now , there is an estimated 1/4 or 25% of the world’s oil and natural gas here. Unfortunately, these are yet accessible because of the amount of ice or snow covering. With increase in technological advancements, this might be accessible in the nearest future

7 0

3 years ago

An independent variable is:

weqwewe [10]

Answer: The variable that you change in an experiment

Explanation: It does not rely on any other factors that deal with the experiment

6 0

2 years ago