8. Rewrite each of the following as an "ordinary” decimal

A 1.540 gram sample of an alloy containing only tin and zinc was reacted with excess fluorine gas to produce 2.489 grams in tota

sineoko [7]

Answer:

Tin: 54.3%

Zinc: 45.7%

Explanation:

The molar masses of the elements are:

Tin: Sn = 117.710 g/mol

Zinc: Zn = 65.409 g/mol

Fluorine: F = 18.998 g/mol

The fluorine gas in excess, so the reaction consumes all the alloy, and all the tin is converted to SnF₄ and all the zinc is converted to ZnF₂. The molar masses of the fluorides are:

SnF₄ = 117.710 + 4*18.998 = 193.702 g/mol

ZnF₂ = 65.409 + 2*18.998 = 103.405 g/mol

If we call x the number of moles of SnF₄, and y the number of moles of ZnF₂, the total mass can be calculated knowing that the mass is the number of moles multiplied by the molar mass:

193.702x + 103.405y = 2.489

The number of moles of Sn is the same as SnF₄ (1:1), and also the number of moles of Zn is the same as ZnF₂ (1:1), so the mass of the alloy:

117.710x + 65.409y = 1.540

if we multiply it by -1.581 and sum with the other equation:

117.710x*(-1.581) + 65.409y*(-1.581) + 193.702x + 103.405y = 1.540*(-1.581) + 2.489

7.60249x = 0.05426

x = 0.0071 mol of Sn

117.710*0.0071 + 65.409y = 1.540

65.409y = 0.704259

y = 0.0108 mol of Zn

The masses are the molar mass multiplied by the number of moles:

Sn: 117.710*0.0071 = 0.836 g

Zn: 65.409*0.0108 = 0.704 g

The percent composition is the mass of the substance divided by the total mass multiplied by 100%:

Sn: (0.836/1.540)*100% = 54.3%

Zn: (0.704/1.540)*100% = 45.7%

6 0

3 years ago

CaC2 + 2H2O ⟶ C2H2 + Ca(OH)2

kondaur [170]

0.499 mol

Explanation: M(CaC2) = 64.1 g/mol, n= m/M = 32.0 g/ 64.1 g/ mol= 0.499 mol

Amount of Calcium hydroxide Is same

7 0

3 years ago

(a) (1)

Elis [28]

Explanation:

The ionization energy of an atom is the amount of energy that is required to remove an electron from a mole of atoms in the gas phase:

M(g) ® M+(g) + e-

It is possible to remove more electrons from most elements, so this quantity is more precisely known as the first ionization energy, the energy to go from neutral atoms to cations with a 1+ charge. The second ionization energy is the energy that is required to remove a second electron, to form 2+ cations from 1+ cations:

M+(g) ® M2+(g) + e-

The third ionization energy is the energy required to form 3+ cations:

M2+(g) ® M3+(g) + e-

and so on. Ionization energies are always positive numbers, because energy must be supplied (an endothermic energy change) to separate electrons from atoms. The second ionization energy is always larger than the first ionization energy, because it requires even more energy to remove an electron from a cation than it is from a neutral atom.

The first ionization energy varies in a predictable way across the periodic table. The ionization energy decreases from top to bottom in groups, and increases from left to right across a period. Thus, helium has the largest first ionization energy, while francium has one of the lowest.

From top to bottom in a group, orbitals corresponding to higher values of the principal quantum number (n) are being added, which are on average further away from the nucleus. Since the outermost electrons are further away, they are less strongly attracted by the nucleus, and are easier to remove, corresponding to a lower value for the first ionization energy.From left to right across a period, more protons are being added to the nucleus, but the number of electrons in the inner, lower-energy shells remains the same. The valence electrons feel a higher effective nuclear charge — the sum of the charges on the protons in the nucleus and the charges on the inner, core electrons. The valence electrons are therefore held more tightly, the atom decreases in size (see atomic radius), and it becomes increasingly difficult to remove them, corresponding to a higher value for the first ionization energy.

The following charts illustrate the general trends in the first ionization energy:

Dunno kung tama beng pero trysorry kung mali

8 0

3 years ago

Explain how liquid can enter the gas phase without reaching its boiling point

ioda

Evaporation is a phase transition from the liquid phase to the gas phase that occurs at temperatures below the boiling point at a given pressure.

hope this helps :)

4 0

3 years ago

Over time, an iron nail reacts with water to produce iron oxide, or rust. Which of the following is a signal that rusting has ta

svetlana [45]

Answer: Chemical composition modification (or, physical signal would be color).

6 0

3 years ago

Read 2 more answers