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3 years ago

How many atoms are found in 12.0 grams of Helium?

2 answers:

3 0

<span>Each mole contains Avagodro's number of atoms i.e. 6.023x10^23, so

3 moles x 6.023x10^23 atoms/mole = 18.069x10^23 atoms = 1.8x19^24 atoms </span>

Furkat [3]3 years ago

3 0

<span>One mole of helium has a mass of 4.0 grams. In 12 grams there are 3 moles of He. Each mole contains 6.022x10^23 atoms of helium. Therefore, 3 moles of He will contain 3 times as many atoms or 1.806x10^24 atoms.</span>

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PLZ I NEEEEEEEDDDDDD HELP

MrRa [10]

Answer:

2h+02=h20

Explanation:

2 in front of h on left side

2 in front of h on right side

3 0

3 years ago

Read 2 more answers

A. how do you determine the charge of an element?

NemiM [27]

Answer:

Explanation:

A. The charge on an element is determined by the differences between the number of protons and electrons in an atom.

An atom will have no charges if the number of protons and electrons are the same.

When an atom loses or gains electrons, the number of electrons will either decrease or increase
if the number of electrons is more than the number of protons, the excess electrons is the charge on the atom. And this makes the atom become a negatively charged ion.
if the number of electrons is lesser than the number of protons, the deficient electrons makes the atom a positively charged ion. The number of electrons by which the atom is deficient makes the atom a positively charged ion.

Charge = number of protons - number of electrons

B. Electrons form the charges they do because with the charge, they become stable like the noble gases.

The desire of every atom is to have stable electronic configuration like those of the noble gases.

A potassium atom with a configuration 2 8 8 1 will prefer to lose an electron to become an Argon atom making the ion stable.

3 0

3 years ago

If you are given an unknown liquid that is 1.0 L and has the mass of 500 grams which of the substance would it be. Distilled Wat

kodGreya [7K]

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8 0

3 years ago

What is the total energy change for the following reaction:CO+H2O-CO2+H2

Alekssandra [29.7K]

Answer:

$\large \boxed{\text{-41.2 kJ/mol}}$

Explanation:

Balanced equation: CO(g) + H₂O(g) ⟶ CO₂(g) + H₂(g)

We can calculate the enthalpy change of a reaction by using the enthalpies of formation of reactants and products

$\Delta_{\text{rxn}}H^{\circ} = \sum \left( \Delta_{\text{f}} H^{\circ} \text{products}\right) - \sum \left (\Delta_{\text{f}}H^{\circ} \text{reactants} \right)$

(a) Enthalpies of formation of reactants and products

$\begin{array}{cc}\textbf{Substance} & \textbf{$\Delta_{\text{f}}$H/(kJ/mol}) \\\text{CO(g)} & -110.5 \\\text{H$_{2}$O} & -241.8\\\text{CO$_{2}$(g)} & -393.5 \\\text{H$_{2}$(g)} & 0 \\\end{array}$

(b) Total enthalpies of reactants and products

$\begin{array}{ccr}\textbf{Substance} & \textbf{Contribution)/(kJ/mol})&\textbf{Sum} \\\text{CO(g)} & -110.5& -110.5 \\\text{H$_{2}$O(g)} &-241.8& -241.8\\\textbf{Total}&\textbf{for reactants} &\mathbf{ -352.3}\\&&\\\text{CO}_{2}(g) & -393.5&-393.5 \\\text{H}_{2} & 0 & 0\\\textbf{Total}&\textbf{for products} & \mathbf{-393.5}\end{array}$

(c) Enthalpy of reaction $\Delta_{\text{rxn}}H^{\circ} = \sum \left( \Delta_{\text{f}} H^{\circ} \text{products}\right) - \sum \left (\Delta_{\text{f}}H^{\circ} \text{reactants} \right)= \text{-393.5 kJ/mol - (-352.3 kJ/mol}\\= \text{-393.5 kJ/mol + 352.3 kJ/mol} = \textbf{-41.2 kJ/mol}\\ \text{The total enthalpy change is $\large \boxed{\textbf{-41.2 kJ/mol}}$}$

4 0

3 years ago

The elements in which electrons are progressively filled in 4f-orbital are called.

Y_Kistochka [10]

The elements in which electrons are progressively filled in 4f-orbital are called lanthanoids.

There are 15 metallic chemical elements called lanthanoids.

Those elements are with atomic numbers from 57 to 71.

Lanthanoids belong to f-block elements because of the filling of the 4f-orbitals.

One of the lanthanoids, lutetium (chemical symbol Lu) has 14 electrons if 4f orbitals.

Electron configuration of lutetium: [Xe] 4f14 5d1 6s2

f-orbitals are similar to the d orbital, but cut in half (eight lobes instead of four).

Lanthanoids are used not as materials in catalysts, alloys, lasers and cathode-ray tubes.

More info about lanthanoids: brainly.com/question/24413965

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5 0

1 year ago