About how many elements are found on the periodic table? Question 8 options:

A 15.0-L scuba diving tank contains a helium-oxygen (heliox) mixture made up of 23.0 g of He and 4.14 g of O2 at 298 K. Calculat

EleoNora [17]

Answer: The mole fraction of Helium is 0.978 and that of oxygen gas is 0.022

Explanation:

To calculate the number of moles, we use the equation:

$\text{Number of moles}=\frac{\text{Given mass}}{\text{Molar mass}}$ .....(1)

For helium:

Given mass of helium = 23 g

Molar mass of helium = 4 g/mol

Putting values in equation 1, we get:

$\text{Moles of helium}=\frac{23g}{4g/mol}=5.75mol$

For oxygen gas:

Given mass of oxygen gas = 4.14 g

Molar mass of oxygen gas = 32 g/mol

Putting values in equation 1, we get:

$\text{Moles of oxygen gas}=\frac{4.14g}{32g/mol}=0.129mol$

Mole fraction of a substance is given by:

$\chi_A=\frac{n_A}{n_A+n_B}$

For helium:

Moles of helium = 5.75 moles

Total moles = [5.75 + 0.129] = 5.879 moles

Putting values in above equation, we get:

$\chi_{(He)}=\frac{5.75}{5.879}=0.978$

For oxygen gas:

Moles of oxygen gas = 0.129 moles

Total moles = [5.75 + 0.129] = 5.879 moles

Putting values in above equation, we get:

$\chi_{(O_2)}=\frac{0.129}{5.879}=0.022$

Hence, the mole fraction of Helium is 0.978 and that of oxygen gas is 0.022

3 0

4 years ago

At what point would a chemical bond form between two atoms.

PIT_PIT [208]

Answer:Chemical bonds form when the valence electrons of one atom interact with the valence electrons of another atom.J

Explanation: Byee stay safe: Wear your mask, drink water and stan bts

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5 0

2 years ago

0.50 g of hydrogen chloride (HCl) is dissolved in water to make 4.0 L of solution. What is the pH of the resulting hydrochloric

svlad2 [7]

Explanation:

Given the mass of HCl is ---- 0.50 g

The volume of solution is --- 4.0 L

To determine the pH of the resulting solution, follow the below-shown procedure:

1. Calculate the number of moles of HCl given by using the formula:

$number of moles of a substance=\frac{given mass of the substance}{its molecular mass}$

2. Calculate the molarity of HCl.

3. Calculate pH of the solution using the formula:

$pH=-log[H^+]$

Since HCl is a strong acid, it undergoes complete ionization when dissolved in water.

$HCl(aq)->H^+(aq)+Cl^-(aq)$

Thus, $[HCl]=[H^+]$

Calculation:

1. Number of moles of HCl given:

$number of moles of a substance=\frac{given mass of the substance}{its molecular mass}\\=0.50g/36.5g/mol\\=0.0137mol$

2. Concentration of HCl:

$Molarity of HCl=\frac{number of moles of HCl}{its molar mass}\\=\frac{0.0137 mol}{4.0 L} \\= 0.003425 M$

3. pH of the solution:

$pH=-log[H^+]\\=-log(0.003425)\\=2.47$

Hence, pH of the given solution is 2.47.

3 0

3 years ago

Calculemos la formula empirica y molecular de carbonato de hierro Fe2(co3)3.Fe.38.3%C.12.3%.0.4 92% masa 292g

DENIUS [597]

Respuesta:

292 g / mol;

Por favor, consulte la explicación.

Explicación:

El número de átomos de cada elemento en el compuesto: Fe2 (co3) 3.

Fe = 2; C = 3; 0 = 3 * 3 = 9

Fe2 = 112 g / mol

C = 12 g / mol

O = 16 g /

Masa molecular = ((112 + (12 * 3) + (16 * 9)

= (112 + 36 + 144)

= 292 g / mol.

Total = 2 + 3 + 9 = 14

Fe2 = 112/292 * 100% = 38,356%

C = 36/292 * 100% = 12,328 * '

O = (16 * 9) / 292 * 100% = 49,32%

7 0

3 years ago

What is 694,563,239 rounded to the nearest thousand

lina2011 [118]

694,563,239 rounded to the nearest thousand is 694,563.

It's because the first digit from the right is for ones, second for tens, third for hundreds and fourth for thousands and that's the one that we should take a closer look at. You can round it either to 3 or 4, depends on the digit of hundreds. In this case 3239 is clearly closer to 3000 than 4000, that's why we round it to 694,563, not 694,564.

6 0

3 years ago

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