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3 years ago

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• describe/recognize the molecular structure of water. • define these terms o matter o element o atom • know and be able to defi

ne the subatomic particles found in atoms. • define atomic number and atomic mass. • be able to determine the reactivity of an element by how many electrons are in the valence shell. • distinguish between ionic, covalent, polar covalent, nonpolar covalent and hydrogen bonds. • state the difference between a compound and a molecule.

1 answer:

artcher [175]3 years ago

4 0

Good luck buddy hhjjjjjjj

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Predict the sign of the entropy change of the system for each of the following reactions.

storchak [24]

Answer :

(a) The entropy change will also decreases.

(b) The entropy change will also increases.

(c) The entropy change will also decreases.

(d) The entropy change will also increases.

Explanation :

Entropy : It is defined as the measurement of randomness or disorderedness in a system.

The order of entropy will be,

As we are moving from solid state to liquid state to gaseous state, the entropy will be increases due to the increase in the disorderedness.

As we are moving from gaseous state to liquid state to solid state, the entropy will be decreases due to the decrease in the disorderedness.

(a) $N_2(g)+3H_2(g)\rightarrow 2NH_3(g)$

In this reaction, the randomness of reactant molecules are more and as we move towards the formation of product the randomness become less that means the degree of disorderedness decreases. So, the entropy change will also decreases.

(b) $CaCO_3(s)\rightarrow CaO(s)+CO_2(g)$

In this reaction, the randomness of reactant molecules are less and as we move towards the formation of product the randomness become more that means the degree of disorderedness increase. So, the entropy change will also increases.

(c) $3C_2H_2(g)\rightarrow C_6H_6(g)$

In this reaction, 3 mole of gaseous $C_2H_2$ react to give 1 mole of gaseous $C_6H_6$ that means randomness become less that means the degree of disorderedness decreases. So, the entropy change will also decreases.

(d) $Al_2O_3(s)+3H_2(g)\rightarrow 2Al(s)+3H_2O(g)$

In this reaction, the number of moles of gases are same on both side of the reaction but 1 mole of solid $Al_2O_3$ react to give 2 moles of solid aluminium that means randomness become more that means the degree of disorderedness increases. So, the entropy change will also increases.

5 0

3 years ago

Match each of the following descriptions to thecorrect element listed

Slav-nsk [51]

Answer: Please see explanation for answer

Explanation:Matching the descriptions to the correct element listed gives

Element Group Name Group No Metal/ Nonmetal/ Metalloid Description

Neon Noble gases 18 Non metal Colorless, tasteless, and odorless gas, unreactive, nonconductive.

Bromine Halogens 17 Non metal Not found as a free element (uncombined) in nature, reddish-brown liquid that vaporizes readily at room temperature to a red gas with a strong disagreeable odor.

Beryllium Alklaline earth metal 2 Metal Silvery-white, ductile, malleable, conductive solid with a high melting point for this type of element

Platinum Platimum group metals 10 Metal Silvery white, relatively soft, low density, conductive solid that is not found as a free element in nature but commonly found combined in alloys with copper or nickel

Potassium Alkali Metals 1 Metal Soft, easily cut with a knife to expose a silvery surface that rapidly oxidizes in air; never found uncombined in nature

Silicon Carbon family 1`4 Metalloid Metallic luster and grayish solid, very common in rocks and gemstones such as amethyst and opal, semiconductor

Sulfur Calcogens 16 Non metal Pale yellow, odorless, brittle solid at room temperature, nonconductor

4 0

3 years ago

Why do people poop it is for my chemistry class

algol13

The digestive system takes the nutrients from the food you eat as well as the water. The leftover matter is excreted through the body as feces, or poop. Hope I helped :)

3 0

3 years ago

Read 2 more answers

Each liter of air has a mass of 1.80 grams. How many liters of air are contained in

g100num [7]

Answer:

25kg

Explanation:

3 0

3 years ago

If the molar absorptivity constant for the red dye solution is 5.56×104 M-1cm-1, calculate the molarity of the red dye solution

Shtirlitz [24]

Explanation:

a) Using Beer-Lambert's law :

Formula used :

$A=\epsilon \times c\times l$

where,

A = absorbance of solution = 0.945

c = concentration of solution = ?

l = length of the cell = 1.20 cm

$\epsilon$ = molar absorptivity of this solution = $5.56\times 10^4 M^{-1} cm^{-1}$

$0.945=5.56\times 10^4 M^{-1} cm^{-1}\times 1.20 \times c$

$c=1.4163\times 10^{-5} M=14.16 \mu M$

( $1\mu M=10^{-6} M$ )

14.16 μM is the molarity of the red dye solution at the optimal wavelength 519nm and absorbance value 0.945.

b) $c=1.4163\times 10^{-5} mol/L$

1 L of solution contains $1.4163\times 10^{-5}$ moles of red dye.

Mass of $1.4163\times 10^{-5}$ moles of red dye:

$1.4163\times 10^{-5}\times 879.86g/mol=0.01246 g$

$(w/v)\%=\frac{\text{Mass of solute (g)}}{\text{Volume of solvent (mL)}}\times 100$

$red(w/v)\%=\frac{0.01246 g}{1000 mL}\times 100=0.001246\%$

c) In order to dilute red dye solution by 5 times, we will need to add 1 L of water to solution of given concentration.

Concentration of red dye solution = $c=1.4163\times 10^{-5} M$

Concentration of red solution after dilution = c'

$c=c'\times 5$

$1.4163\times 10^{-5} M=c'\times 5$

$c'=2.83\times 10^{-6} M$

The final concentration of the diluted solution is $2.83\times 10^{-6} M$

8 0

3 years ago