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3 years ago

How many total electron will fit in the 1st energy level

Chemistry

2 answers:

Vlad1618 [11]3 years ago

7 0

2, only 2 electrons fit in the 1st energy level or ring

nevsk [136]3 years ago

4 0

2 elections will fill the first energy level

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A 0.105 L sample of an unknown HNO 3 solution required 35.7 mL of 0.250 M Ba ( OH ) 2 for complete neutralization. What is the c

oksano4ka [1.4K]

Answer: 0.17M

Explanation:

The equation for the reaction is :

2HNO3 + Ba(OH)2 —> Ba(NO3)2 + 2H2O

From the balanced equation, we obtain :

nA = mole of acid = 2

nB = mole of the base = 1

From the question, we obtain:

Va = Vol. Of acid = 0.105L

Ma = conc. Of acid =?

Vb = Vol of base = 35.7 mL = 0.0357L

Mb = conc. of base = 0.25M.

We solve for the conc. of the acid using:

MaVa / Mb Vb = nA / nB

(Ma x 0.105) / (0.25x0.0357) = 2

Cross multiply to express in linear form. We have:

Ma x 0.105 = 0.25 x 0.0357 x 2

Divide both side by 0.105. We have

Ma = (0.25 x 0.0357 x 2) / 0.105

Ma = 0.17M

Therefore the concentration of the acid(HNO3) is 0.17M

3 0

3 years ago

What is the net charge of the ionic compound calcium fluoride

yKpoI14uk [10]

Answer:

The net charge of the ionic compound calcium fluoride is zero (0).

Explanation:

Ionic compounds, such as covalent ones, have zero net charge; this is, they are neutral.

Substances with net positive charge are cations and substances with net negative charge are anions.

The charges in the ionic compound calcium flouride are distributed in this way:

Compound formula: CaF₂

Calcium charge: Ca²⁺: this is, each calcium ion has a 2 positive charge

Fluoride charge: F⁻: each fluoride ion has a 1 negative charge.

Then, the net charge is: 1 × (2+) + 2 × (1-) = +2 - 2 = 0.

So, a two positve charge, from one calcium ion, is equal to two negative charges, from two fluoride tions, yielding a zero net charge.

8 0

3 years ago

When 0.620 gMngMn is combined with enough hydrochloric acid to make 100.0 mLmL of solution in a coffee-cup calorimeter, all of t

OleMash [197]

Answer:

The enthalpy change during the reaction is -199. kJ/mol.

Explanation:

$Mn(s)+2HCl(aq)\rightarrow MnCl_2(aq)+H_2(g)$

Mass of solution = m

Volume of solution = 100.0 mL

Density of solution = d = 1.00 g/mL

$m=1.00 g/mL\times 100.0 mL = 100 g$

First we have to calculate the heat gained by the solution in coffee-cup calorimeter.

$q=m\times c\times (T_{final}-T_{initial})$

where,

m = mass of solution = 100 g

q = heat gained = ?

c = specific heat = $4.18 J/^oC$

$T_{final}$ = final temperature = $23.1^oC$

$T_{initial}$ = initial temperature = $28.9^oC$

Now put all the given values in the above formula, we get:

$q=100 g \times 4.18 J/^oC\times (28.9-23.1)^oC$

$q=2,242.4 J=2.242 kJ$

Now we have to calculate the enthalpy change during the reaction.

$\Delta H=-\frac{q}{n}$

where,

$\Delta H$ = enthalpy change = ?

q = heat gained = 2.242 kJ

n = number of moles fructose = $\frac{\text{Mass of manganese}}{\text{Molar mass of manganese}}=\frac{0.620 g}{54.94 g/mol}=0.0113 mol$

$\Delta H=-\frac{2.242 kJ}{0.0113 mol }=-199. kJ/mol$

Therefore, the enthalpy change during the reaction is -199. kJ/mol.

8 0

3 years ago

A cup of coffee has 71 mL of coffee and 127 mL of water. What is the percent volume of the coffee solution?

Anna [14]

Answer:

35.9%

Explanation:

The percent volume of the coffee solution can be calculated as follows:

% volume of coffee solution = volume of coffee/total volume of coffee solution × 100

According to this question, a cup of coffee has 71 mL of coffee and 127 mL of water. This means that, the total volume of coffee solution is;

71mL + 127mL = 198mL

% volume = 71/198 × 100

= 0.359 × 100

Percent volume of coffee solution = 35.9%

3 0

3 years ago

Why is it important to heat analytical reagents and store them in a dessicated atmosphere before use?

schepotkina [342]

Explanation:

In normal atmosphere, analytical reagents may absorb water molecules that may affect the results of chemical reactions. So, in order to get accurate results from these analytical regents, they must be stored in a dessicated atmosphere or heated before being used so that the water molecules must dry away.

5 0

3 years ago