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4 years ago

Help Me Please

2 answers:

6 0

in the periodic table, elements are classified in the ascending order of their atomic numbers. atomic number is the number of protons

in elements the number of protons is equal to the number of electrons

the condensed notation of electron configuration is when the symbol of the noble gas closest to the elements electron configuration is mentioned.

[He] 2s² - number of electrons in He is 2 , and 2 more electrons in the s subshell adds upto a sum of 4 electrons. number of protons = number of electrons

then number of protons = 4

then atomic number is 4. element with atomic number 4 is Be

the element is Be

[Ne] 3s² 3p⁵

Ne atomic number is 10. 10 + 7 electrons in the third shell = 17 electrons in total

atomic number - 17 is Cl

element is Cl

[Xe] 6s¹

Xe atomic number is 54, 54 + 1 electron in the sixth shell = 55 electrons in total

atomic number of 55 is Cs

element is Cs

[Ar] 4s² 3d⁹

Ar atomic number is 18. 18 + 2 electrons in 4th shell and 9 in d subshell of 3rd shell = 29 electrons in total

atomic number of 29 is Cu

element is Cu

Shtirlitz [24]4 years ago

6 0

[He]2s2: Be
[Ne]3s23p5: Cl
[Xe]6s1: Cs
<span> [Ar]4s23d9: Cu</span>

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500 mL solution of calcium chloride with a concentration of 0.75 mol/L. The mass of solute needed to make this solution is ___ _

BabaBlast [244]

Answer:

41.63g

Explanation:

Given parameters:

Volume of CaCl₂ = 500mL = 0.5L

Concentration = 0.75mol/L

Unknown:

Mass of the solute needed = ?

Solution:

The mass of the solute can be derived using the expression below;

Mass = number of moles x molar mass

But,

Number of moles = Concentration x Volume

So;

Mass = Concentration x Volume x molar mas

Molar mass of CaCl₂ = 40 + 2(35.5) = 111g/mol

Mass = 0.75 x 0.5 x 111 = 41.63g

5 0

3 years ago

A chemist mixes 1.00 g CuCl2 with an excess of (NH4)2HPO4 in dilute aqueous solution . He measures the evolution of 670 J of hea

kaheart [24]

Answer:

$\Delta H$ will be 90054 J

Explanation:

Number of moles = (mass)/(molar mass)

Molar mass of $CuCl_{2}$ = 134.45 g/mol

So, 1.00 g of $CuCl_{2}$ = $\frac{1.00}{134.45}mol$ of $CuCl_{2}$ = 0.00744 mol of $CuCl_{2}$

0.00744 mol of $CuCl_{2}$ produces 670 J of heat

So, 1 mol of $CuCl_{2}$ produces $\frac{670}{0.00744}J$ of heat or 90054 J of heat

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4 years ago

Which part of Earth most likely has the highest albedo value?

photoshop1234 [79]

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3 years ago

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meriva

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3 years ago

The Haber process can be used to produce ammonia (NH3) from hydrogen gas (H2) and nitrogen gas (N2). The balanced equation for t

kotykmax [81]

Answer:

Explanation:

We are given that ammonia can be produced from hydrogen gas and nitrogen gas according to the equation:

$\displaystyle 3\text{H$_2$} + \text{N$_2$} \longrightarrow 2\text{NH$_3$}$

We want to determine the mass of hydrogen gas that must have reacted if 0.575 g of NH₃ was produced.

To do so, we can convert from grams of NH₃ to moles of NH₃, moles of NH₃ to moles of H₂, and moles of H₂ to grams of H₂.

We are given that the molar masses of NH₃ and H₂ are 17.03 g/mol and 2.0158 g/mol, respectively.

From the equation, we can see that two moles of NH₃ is produced from every three moles of H₂.

With the initial value, perform dimensional analysis:

$\displaystyle \begin{aligned} 0.575\text{ g NH$_3$}& \cdot \frac{1\text{ mol NH$_3$}}{17.03\text{ g NH$_3$}} \cdot\frac{3\text{ mol H$_2$}}{2\text{ mol NH$_3$}} \cdot \frac{2.0158\text{ g H$_2$}}{1\text{ mol H$_2$}} \\ \\ & = 0.102\text{ g H$_2$}\end{aligned}$

*Assuming 100% efficiency.

Our final answer should have three significant figures. (The first term has three, the second term has four (the one is exact), the third term is exact, and the fourth term has five. Hence, the product should have only three.)

In conclusion, our answer is B.

3 0

3 years ago