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Karo-lina-s [1.5K]
2 years ago
7

Many metals pack in cubic unit cells. The density of a metal and length of the unit cell can be used to determine the type for p

acking. For example, polonium has a density of 9.19 g/cm3 and a unit cell side length a of 3.37 Å. (1 Å = 1 10-8 cm.) (a) How many polonium atoms are in exactly 1 cm3? atoms (b) How many unit cells are in exactly 1 cm3? unit cells (c) How many polonium atoms are there per unit cell?
Chemistry
1 answer:
jarptica [38.1K]2 years ago
3 0

Answer:

A.) 34.866 x 10¯23 g/atom

B.) 2.64 x 10^22 atoms in 1 cm3

C.) 1 atoms per unit cell

Explanation:

A) Calculate the average mass of one atom of polonium:

210g mol¯1 ÷ 6.022 x 1023 atoms mol¯1 = 34.866 x 10¯23 g/atom

B) Determine atoms in 1 cm3:

9.19g / 34.866x 10¯23 g/atom = 2.64 x 10^22 atoms in 1 cm3

Determine volume of the unit cell:

(3.37 x 10¯8 cm)3 = 3.827 x 10¯23 cm3

Determine number of unit cells in 1 cm3:

1 cm3 / 3.827 x 10¯23 cm3 = 2.61 x 1022 unit cells

C) Determine atoms per unit cell:

2.64 x 1022 atoms / 2.61 x 1022 unit cells = 1 atoms per unit cell

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Consider these generic half-reactions. Half-reaction E° (V) X+(aq)+e−⟶X(s) 1.52 Y2+(aq)+2e−⟶Y(s) −1.17 Z3+(aq)+3e−⟶Z(s) 0.84 Ide
olya-2409 [2.1K]

Answer:

     strongest oxidizing agent: X^{+}

     weakest oxidizing agent: Y^{2+}

     strongest reducing agent: Y

     weakest reducing agent: X

     X^{+} will oxidize Z

Explanation:

The higher the reduction potential of a species, higher will be the tendency to consume electrons from another species. Hence higher will be the oxidizing power of it's oxidized form and lower will be the reducing power of it's reduced form.

Alternatively, higher reduction potential value suggests that the oxidized form of the species acts as a stronger oxidizing agent and the reduced form of the species acts as a weaker reducing agent.

Order of reduction potential:

                       E_{X^{+}\mid X}^{0}(1.52V)> E_{Z^{3+}\mid Z}^{0}(0.84V)> E_{Y^{2+}\mid Y}^{0}(-1.17V)

So, strongest oxidizing agent: X^{+}

     weakest oxidizing agent: Y^{2+}

     strongest reducing agent: Y

     weakest reducing agent: X

As reduction potential of the half cell X^{+}\mid X is higher than the reduction potential of the half cell Z^{3+}\mid Z therefore X^{+} will oxidize Z into Z^{3+} and itself gets converted into X.

     

5 0
2 years ago
A gas that has a volume of 28 liters, a temperature of 45C, And an unknown pressure has its volume increased to 34 liters and it
patriot [66]

Answer:

P1 = 2.5ATM

Explanation:

V1 = 28L

T1 = 45°C = (45 + 273.15)K = 318.15K

V2 = 34L

T2 = 35°C = (35 + 273.15)K = 308.15K

P1 = ?

P2 = 2ATM

applying combined gas equation,

P1V1 / T1 = P2V2 / T2

P1*V1*T2 = P2*V2*T1

Solving for P1

P1 = P2*V2*T1 / V1*T2

P1 = (2.0 * 34 * 318.15) / (28 * 308.15)

P1 = 21634.2 / 8628.2

P1 = 2.5ATM

The initial pressure was 2.5ATM

3 0
2 years ago
Just Lemons Lemonade Recipe Equation:
zalisa [80]

Answer:

Explanation:

Hello!

<em>Complete text:</em>

<em>Honors Stoichiometry Activity WorksheetInstructions: </em>

<em>Activity Two: Just Lemons, Inc. Production</em>

<em>Here's a one-batch sample of Just Lemons lemonade production. Determine the percent yield and amount of leftover ingredients for lemonade production and place your answers in the data chart.</em>

<em>Hint: Complete stoichiometry calculations for each ingredient to determine the theoretical yield. Complete a limiting reactant-to-excess reactant calculation for both excess ingredients. </em>

<em>Water 946.36 g </em>

<em>Sugar 196.86 g </em>

<em>Lemon Juice 193.37 g </em>

<em>Lemonade 2050.25g</em>

<em>Leftover Ingredients?</em>

<em>Just Lemons Lemonade Recipe Equation:</em>

<em>2 water + sugar + lemon juice = 4 lemonade</em>

<em>Mole conversion factors:</em>

<em>1 mole of water = 1 cup = 236.59 g</em>

<em>1 mole of sugar = 1 cup = 225 g</em>

<em>1 mole of lemon juice = 1 cup = 257.83 g</em>

<em>1 mole of lemonade = 1 cup = 719.42 g</em>

You have the information on the ingredients used to produce one batch of lemonade and the amount of lemonade produced. To determine which ingredients be leftovers, you have to determine first, which one is the limiting reactant, i.e. the ingredient that will be used up first.

According to the recipe, to make 4 moles of lemonade, you use 2 moles of water, one mole of sugar and one mole of lemon juice, expressed in grams:

2 water  + sugar + lemon juice = 4 lemonade

2*(236.59) + 225g + 257.83g  = 4*(719.42)g

    473.18g + 225g + 257.83g = 2877.68g

So for every 2877.68g of lemonade made, they use 473.18g of water, 225g of sugar, and 257.83g of lemon juice.

You know that they made a batch of 2050.25g, so to detect the limiting reactant, first, you have to calculate, in theory, how much of each ingredient you need to make the given amount of lemonade:

Use cross multiplication

<u>Water:</u>

2877.68g lemonade → 473.18g water

2050.25g lemonade → X= (2050.25*473.18)/2877.68= 337.12g water

Following the recipe, to elaborate 2050.25g of lemonade, you need to use 337.12g of water.

<u>Sugar:</u>

2877.68g lemonade → 225g sugar

2050.25g lemonade → X= (2050.25*225)/2877.68= 160.30g sugar.

To elaborate 2050.25f of lemonade you need to use 160.30g of sugar.

<u>Lemon juice:</u>

2877.68g lemonade → 257.83g lemon juice

2050.25g lemonade → X= (2050.25*257.83)/2877.68= 183.69g lemon juice.

To elaborate 2050.25f of lemonade you need to use 183.69g lemon juice.

Available ingredients vs. theoretical yields for 2050.25g of lemonade:

Water 946.36 g → 337.12g

Sugar 196.86 g → 160.30g

Lemon Juice 193.37 g → 183.69g

The lemon juice will be the first ingredient to be used up, there will be a surplus of water and sugar.

I hope this helps!

7 0
2 years ago
Which of the following statements describe chemical properties?
Y_Kistochka [10]

Answer:

  • <em><u>A. Oxygen gas supports combustion.</u></em>
  • <em><u>B. Hydrofluoric acid reacts with glass.</u></em>
  • <em><u>C. Fertilizers help to increase agricultural production. </u></em>

Explanation:

<em>Chemical properties</em> can only be observed when a chemical change, i.e. a change in the chemical composition, occurs.

On the other hand,  physical properties are observed or measured without altering the composition of the substances.

Typical examples of chemical properties are reactivity, flammability, combustion, oxidation states, acidity, among others that require to carry out a chemical reaction to be observed.

Typical examples of physical properties are freezing point, melting point, boiling point, density, solubility, corrosiveness, among others.

Thus, as for the choices you have:

<em><u>A. Oxygen gas supports combustion:</u></em> the only way to observe this property is by carrying out a combustion reaction, so this describes a chemical property.

<u><em>B. Hydrofluoric acid reacts with glass:</em></u> again, only by letting hydrofluoric acid react with glass this can be observed, so this is another example of a chemical property.

<u><em>C. Fertilizers help to increase agricultural production:</em></u> fertilizers are absorbed by the plants and converted by biochemical reactions, so this also describes a chemical property.

<em><u>D. Water boils below 100°C on top of a mountain:</u></em> boiling is a change of state, the water is H₂O and continues having the same composition after boiling, so this describes a physical property.

<em><u>E. Lead is denser than aluminum: </u></em>density is measured by physical media, measuring mass and volume; so this is a physical property.

4 0
2 years ago
Aluminum has a density of 2.70 g/mL. Calculate the mass (in grams) of a piece of aluminum having a volume of 276 mL .
garri49 [273]
Mass = ?

Density = 2.70 g/mL

Volume = 276 mL

Therefore:

D = m / V

2.70 = m / 276

m = 2.70 x 276

m = 745.2 g

5 0
2 years ago
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