Hypothesize! What type of substance do you think Coffee is? Why?

Which of the following choices would have a positive entropy change?

aalyn [17]

Answer:

The option B) Fe₂O₃ (s) + 3C(s) → 2Fe(s) + 3CO₂(g), because the reactants are only solid units and the products contain gas molecules.

Explanation:

A positive entropy change means that the entropy of the products is greater than the entropy of the reactants.

Entropy in a measure of the radomness or disorder of the system.

Let's see every reaction:

A) 4NO₂ (g) + 2 H₂O (l) + O₂ (g) → 4 HNO₃ (aq)

Since 5 molecules of a gas (high disorder) combines with 2 molecules of liquid to produce 4 units of aqueous HNO₃ you may expect that the product is more ordered than the reactants, which means that the change in entropy is negative (the entropy decreases).

B) Fe₂O₃ (s) + 3C(s) → 2Fe(s) + 3CO₂(g)

The left side (reactants) show only solid substances which is a highly ordered arrangement while the right side (products) show the formation a solid (ordered arrangement) and a gas (highly disoredered arrangement), so you can predict the increase of the system entropy, i.e. a positive entropy change.

The equation C) shows the combination of 12 gas molecules to produce 1 solid and 6 gas molecules, so you can expect that the entropy will decrease, i.e. a negative entropy change.

For equation D) the products include solid and gas reactants while the product is just one unit of solid substance, letting you to predict a negative entropy change.

4 0

3 years ago

Give the formulas of the compounds in each set (a) lead(l|) oxide and lead(lV) oxide; (b) lithium nitride, lithium nitrite, and

Ivanshal [37]

Answer:

For a: The formula of lead (II) oxide and lead (IV) oxide is $PbO\text{ and }PbO_2$ respectively.

For b: The formula of lithium nitride, lithium nitrite and lithium nitrate is $Li_3N,LiNO_2\text{ and }LiNO_3$ respectively.

For c: The formula of Strontium hydride and strontium hydroxide is $SrH_2\text{ and }Sr(OH)_2$ respectively.

For d: The formula of magnesium oxide and manganese (II) oxide is $MgO\text{ and }MnO$ respectively.

Explanation:

All the given compounds are ionic compounds. This means that between the atoms complete sharing of electrons takes place.

For a:

Lead is the 82th element of periodic table having electronic configuration of $[Xe]4f^{14}5d^{10}6s^26p^2$ .

To form $Pb^{2+}$ ion, this element will loose 2 electrons and to form $Pb^{4+}$ ion, this element will loose 4 electrons.

Oxygen is the 8th element of periodic table having electronic configuration of $[He]2s^22p^4$ .

To form $O^{2-}$ ion, this element will gain 2 electrons.

By criss-cross method, the oxidation state of the ions gets exchanged and they form the subscripts of the other ions. This results in the formation of a neutral compound.

So, the chemical formula for lead (II) oxide is PbO and for lead (IV) oxide is $PbO_2$

Thus, the formula of lead (II) oxide and lead (IV) oxide is $PbO\text{ and }PbO_2$ respectively.

For b:

Lithium is the 3rd element of periodic table having electronic configuration of $[He]2s^1$ .

To form $Li^{+}$ ion, this element will loose 1 electron.

Nitrogen is the 7th element of periodic table having electronic configuration of $[He]2s^22p^3$ .

To form $N^{3-}$ ion, this element will gain 3 electrons.

Nitrite ion is a polyatomic ion having chemical formula of $NO_2^{-}$

Nitrate ion is a polyatomic ion having chemical formula of $NO_3^{-}$

By criss-cross method, the oxidation state of the ions gets exchanged and they form the subscripts of the other ions. This results in the formation of a neutral compound.

So, the chemical formula for lithium nitride is $Li_3N$ , for lithium nitrite is $LiNO_2$ and for lithium nitrate is $LiNO_3$

Thus, the formula of lithium nitride, lithium nitrite and lithium nitrate is $Li_3N,LiNO_2\text{ and }LiNO_3$ respectively.

For c:

Strontium is the 38th element of periodic table having electronic configuration of $[Kr]5s^2$ .

To form $Sr^{2+}$ ion, this element will loose 2 electrons.

Hydrogen is the 1st element of periodic table having electronic configuration of $1s^1$ .

To form $H^{-}$ ion, this element will gain 1 electron and is named as hydride ion.

Hydroxide ion is a polyatomic ion having chemical formula of $OH^{-}$

By criss-cross method, the oxidation state of the ions gets exchanged and they form the subscripts of the other ions. This results in the formation of a neutral compound.

So, the chemical formula for strontium hydride is $SrH_2$ and for strontium hydroxide is $Sr(OH)_2$

Thus, the formula of Strontium hydride and strontium hydroxide is $SrH_2\text{ and }Sr(OH)_2$ respectively.

For d:

Magnesium is the 12th element of periodic table having electronic configuration of $[Ne]3s^2$ .

To form $Mg^{2+}$ ion, this element will loose 2 electrons.

Manganese is the 25th element of the periodic table having electronic configuration of $[Ar]3d^54s^2$

To form $Mn^{2+}$ ion, this element will loose 2 electrons.

Oxygen is the 8th element of periodic table having electronic configuration of $[He]2s^22p^4$ .

To form $O^{2-}$ ion, this element will gain 2 electrons.

By criss-cross method, the oxidation state of the ions gets exchanged and they form the subscripts of the other ions. This results in the formation of a neutral compound.

So, the chemical formula for magnesium oxide is MgO and for manganese (II) oxide is MnO.

Thus, the formula of magnesium oxide and manganese (II) oxide is $MgO\text{ and }MnO$ respectively.

7 0

3 years ago

Why is ammonia (NH₃) classified as a polar molecule?

aleksandr82 [10.1K]

Answer:

Ammonia contains an asymmetrical distribution of electric charge.

Explanation:

Hello there!

In this case, accordingly to the electronegativity difference we can calculate for the N-H bond, and based off our periodic table, which shows an electronegativity of 3.0 and 2.1 for N and H respectively, we obtain:

$DE=3.0-2.1=0.9$

Which is within the range of polar molecule even the both of them are nonmetals. Thus, choices a and b are firstly discarded; nonetheless, even when they are both nonmetals, two of these elements usually have a nonpolar bond, which means that option C is discarded, and therefore, our answer is ammonia contains an asymmetrical distribution of electric charge.

Regards!

6 0

3 years ago

What molecules have 5 carbon atoms and 12 hydrogen atoms

goldfiish [28.3K]

ANSWER

THE PENTANES

EXPLANATION

he word for5 in Greek is PENT like the 5 sided and 5 angled building in Wachington the PENTagon.

SO C5H12 IS PENTAND BECAUSE IT HAS NO DOUBLE BONDAS IT IS AN ALKANE

SO SO C5H12 IS PENT-ANE PENTANE AND THERE ARE MULTIPLE FORMS OF IT

4 0

3 years ago

5. Selenium-83 has a half-life of 25.0 minutes. How many minutes would it take for a 10.0

scZoUnD [109]

Explanation:

10.0mg / 1.25mg = 8

1/8 of the original mass => 3 half-life phases

Hence it will take 25.0 min * 3 = 75.0min.

7 0

3 years ago

Hypothesize!​ What type of substance do you think Coffee is? Why?

Hypothesize! What type of substance do you think Coffee is? Why?