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4 years ago

Dilutions Worksheet - Solutions

Chemistry

1 answer:

xxMikexx [17]4 years ago

3 0

Answer:

$\large \boxed{\text{0.64 mol/L}}$

Explanation:

The original solution was diluted from 250 mL to 295 mL

We can use the dilution formula to calculate the concentration of the diluted solution.

$\begin{array}{rcl}V_{1}c_{1} & = & V_{2}c_{2}\\\text{250 mL }\times \text{0.75 mol/L} & = & \text{295 mL} \times c_{2}\\c_{2}& = & \dfrac{250}{295}\times \text{0.75 mol/L}\\\\& = & \text{0.64 mol/L}\\\end{array}\\\text{The molar concentration of the diluted solution is $\large \boxed{\textbf{0.64 mol/L}}$}$

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Rhodium crystallizes in a face-centered cubic unit cell. The radius of a rhodium atom is 135 pm. Determine the density of rhodiu

Deffense [45]

Answer:

Density of unit cell ( rhodium) = 12.279 g/cm³

Explanation:

Given that:

The radius (r) of a rhodium atom = 135 pm

The atomic mass of rhodium = 102.90 amu

For a face-centered cubic unit cell,

$r = \dfrac{a}{2\sqrt{2}}$

where;

a = edge length.

Making "a" the subject of the formula:

$a = 2 \sqrt{2} \times r$

$a = 2 \times 1.414 \times 135 \ pm$

a = 381.8 pm

to cm, we get:

a = 381.8 × 10⁻¹⁰ cm

However, recall that:

$density \ of \ unit \ cell = \dfrac{mass \ of \ unit \ cell}{volume \ of \unit \ cell}$

where;

mass of unit cell = mass of atom × numbers of atoms per unit cell

Also;

$mass\ of\ atom =\dfrac{ atomic \ mass}{Avogadro \ number}$

$mass\ of\ atom =\dfrac{ 102.9}{6.023 \times 10^{23}}$

Recall also that number of atoms in a unit cell for a face-centered cubic = 4

So;

$mass \ of \ unit \ cell= \dfrac{102.90}{6.023 \times 10^{23}}\times 4$

mass of unit cell = 6.83380375 × 10⁻²² g

$Density \ of \ unit \ cell = \dfrac{6.83380375 \times 10^{-22}}{(381.8\times 10^{-10})^3}$

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3 years ago

!: (a) 20 cm: 80

RoseWind [281]

Answer:

THE LENGTH OF THE AIR COLUMN IS 9.5 CM

Explanation:

Taking the atmospheric pressure to be 760 mmHg;

When the capillary tube is held horizontally, the pressure of the tube is 760 mmHg

when the capillary tube is held vertically, the pressure increases by 4 cm = 40 mm

The new pressure of the tube is hence, 760 + 40 mmHg = 800 mmHg

Using the pressure forlmula;

P1 V1 = P2 V2

P1 A1 L1 = P2 A2 L2

where A1 and A2 is the area of the capillary tube and it is equal, it cancels out.

P1 l1 = P2 l2

l2 = P1 l1 / P2

l2 = 760 * 10 / 800

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The length of the air in the tube is 9.5 cm.

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kap26 [50]

Answer:

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Explanation:

Using integrated rate law for first order kinetics as:

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Where,

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