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3 years ago

Which statement best describes the atomic structure of metals

Chemistry

1 answer:

Vikki [24]3 years ago

6 0

Answer:

Closely packed cations with loosely held valence electrons

Explanation:

Pure metals contain so-called metallic bonds. These metallic bonds are often referred to as sea of electrons. Metals consist of closely packed cations (and, hence, that's why they have a high density) with loosely held valence electrons (this is the reason why metals tend to lose their electrons rather than gain, besides, it's also the reason why the first ionization energy for the metals is relatively low).

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A solution is prepared from 26.7 g of an unknown compound and 116.2 g acetone, C3H6O, at 313 K. At this temperature the vapor pr

Cloud [144]

Answer:

The molecular weight of the unknown compound is 267.7 g/mol

Explanation:

Lowering vapor pressure → Colligative property where the vapor pressure of solution is lower than vapor pressure of pure solvent

ΔP = P° . Xm

0.526 atm - 0.501 atm = 0.025atm

0.025 atm = 0.526 atm . Xm

Xm = 0.025 atm / 0.526 atm → 0.0475 (mole fraction)

Mole fraction = Moles of solute / Total moles (solute + solvent)

0.0475 = Moles of solute / Moles of solute + Moles of solvent

We determine the moles of solvent → 116.2 g . 1mol / 58 g = 2 moles

0.0475 = Moles of solute / Moles of solute + 2

0.0475 moles of solute + 0.095 = Moles of solute

0.095 = Moles of solute - 0.0475 moles of solute

0.095 / 0.9525 = Moles of solute → 0.0997 moles

Molas mass = g/mol → 26.7 g / 0.0997 mol = 267.7 g/mol

4 0

3 years ago

Be sure to answer all parts. In the electrolysis of molten BaI2, (a) What product forms at the negative electrode? (b) What prod

Tcecarenko [31]

Answer:

(a) Barium is produced at the negative electrode

(b) Iodine is produced at the positive electrode

Explanation:

When an electric current is passed through a solution containing electrolyte, a non spontaneous reaction is stimulated. This results in the flow of positively charged ions to negatively charged electrodes(cathode) and negatively charged ions to positively charged electrodes(anode)

When an electric current is passed through molten $BaI_{2}$ in the electrolytic cell, the following reactions takes place:

$BaI_{2}$ → $Ba^{2+}$ + 2 $I^{-}$

At the anode;

Iodine ions will lose an electron and will be oxidized to iodine

$2I^{-}$ → $I_{2}$ + $e^{-}$

At the cathode;

Barium ions gains electrons and its reduced to barium metal

$Ba^{2+}$ + $2e^{-}$ → Ba

3 0

3 years ago

A 72.0-gram piece of metal at 96.0 °C is placed in 130.0 g of water in a calorimeter at 25.5 °C. The final temperature in the ca

tekilochka [14]

Answer: The answer is S = 0.1528 cal/g °C

Explanation:

By the law of conservation of energy, energy is neither created nor destroyed.

So, energy lost by metal pieces is equal to the energy gained by water in the calorimeter.

Specific heat of water is 1 cal/g °C

⇒ heat energy Q = mSΔT, where m = mass of a substance

S = specific heat

ΔT = change in temperature

Now, the heat lost by metal piece, Q = 72×S×(96-31)

= 4680×S cal

Heat gained by water, Q = 130×1×(31-25.5)

= 715 cal

⇒ 4680×S = 715.

⇒ S = 0.1528 cal/g °C.

6 0

4 years ago

Helium is the lightest noble gas and the second most abundant element (after hydrogen) in the universe. The mass of a helium−4 a

dmitriy555 [2]

Answer: The fraction of atom's mass contributed by nucleus is 0.99

Explanation:

Nucleons are defined as the sub-atomic particles which are present in the nucleus of an atom. Nucleons are protons and neutrons.

The isotopic symbol of Helium-4 atom is $_2^4\textrm{He}$

Number of electrons = 2

Number of protons = 2

Number of neutrons = 4 - 2 = 2

We are given:

Mass of He-4 atom = $6.64648\times 10^{-24}g$

Mass of 1 electron = $9.10939\times 10^{-28}g$

Calculating the mass contributed by the nucleus = $m_{He}-2(m_e)$

Mass of the nucleus of He-4 atom = $6.64648\times 10^{-24}-(2\times (9.10939\times 10^{-28}))=(6.64648-0.0018219)\times 10^{-24}=6.64466\times 10^{-24}$

To calculate the fraction of atom's mass contributed by the nucleus, we use the equation:

$\text{Fraction of atom's mass contributed by nucleus}=\frac{\text{Mass of nucleus}}{\text{Mass of atom}}$

Putting values in above equation, we get:

$\text{Fraction of atom's mass contributed by nucleus}=\frac{6.64466\times 10^{-24}g}{6.64648\times 10^{-24}g}=0.99$

Hence, the fraction of atom's mass contributed by nucleus is 0.99

8 0

3 years ago

Hydrogen peroxide decomposes in presence of manganese (iv) oxide to give oxygen gas i). Draw a labelled diagram to show the volu

Effectus [21]

Answer:

Oxygen can be made from hydrogen peroxide, which decomposes slowly to form water and oxygen:

hydrogen peroxide → water + oxygen

2H2O2(aq) → 2H2O(l) + O2(g)

The rate of reaction can be increased using a catalyst, manganese(IV) oxide. When manganese(IV) oxide is added to hydrogen peroxide, bubbles of oxygen are given off.

Apparatus arranged to measure the volume of gas in a reaction. Reaction mixture is in a flask and gas travels out through a pipe in the top and down into a trough of water. It then bubbles up through a beehive shelf into an upturned glass jar filled with water. The gas collects at the top of the jar, forcing water out into the trough below.

To make oxygen in the laboratory, hydrogen peroxide is poured into a conical flask containing some manganese(IV) oxide. The gas produced is collected in an upside-down gas jar filled with water. As the oxygen collects in the top of the gas jar, it pushes the water out.

Instead of the gas jar and water bath, a gas syringe could be used to collect the oxygen

6 0

2 years ago