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3 years ago

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An acid sample of an unknown concentration is contained in a erlenmeyer flask. Which technique below would be best suited to ana

lytically determine the number of moles of hcl in the sample?

1 answer:

Ivenika [448]3 years ago

4 0

Answer:

Titration

Explanation:

The best technique which can be used to determine the number of moles of the HCl in the sample is titration.

The given amount of HCl solution must be titrated with known concentration of the base like NaOH.

The volume of NaOH required must be noted also.

According to the reaction,

$NaOH+HCl\rightarrow NaCl+H_2O$

At equivalence point

Moles of $HCl$ = Moles of $NaOH$

Considering:-

Moles of $HCl=Molarity_{NaOH}\times Volume_{NaOH}$

Thus, in this way, moles of HCl can be determined.

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Convert 52.09 km/h into m/s.

Fudgin [204]

Answer:

52.09×5/18

14.44 m/s

I hope it's helps you

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3 years ago

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The unit cell for cr2o3 has hexagonal symmetry with lattice parameters a = 0.4961 nm and c = 1.360 nm. If the density of this ma

IRINA_888 [86]

To calculate the packing factor, first calculate the area and volume of unit cell.

Area is calculated as:

$A=6R^{2}\sqrt{3}$

Here, R is radius and is related to a as follows:

$R=\frac{a}{2}$

Putting the value in expression for area,

$A=6(\frac{a}{2})^{2}\sqrt{3}=1.5a^{2}\sqrt{3}$

The value of a is 0.4961 nm

Since, $1 nm=10^{-7}cm$

Thus, $0.4961 nm=4.961\times 10^{-8} cm$

Putting the value,

$Area=1.5(4.961\times 10^{-8}cm)^{2}\sqrt{3}=6.39\times 10^{-15}cm^{2}$

Now, volume can be calculated as follows:

$V=Area\times c$

The value of c is 1.360 nm or $1.360\times 10^{-7} cm$

Putting the value,

$V=(6.39\times 10^{-15}cm^{2})\times (1.360\times 10^{-7} cm)=8.7\times 10^{-22}cm^{3}$

now, number of atom in unit cell can be calculated by using the following formula:

$n=\frac{\rho N_{A}V_{c}}{A}$

Here, A is atomic mass of $Cr_{2}O_{3}$ is 151.99 g/mol.

Putting all the values,

$n=\frac{(5.22 g/cm^{3})(6.023\times 10^{23} mol^{-1})(8.7\times 10^{-22}cm^{3})}{(151.99 g/mol)}\approx 18$

Thus, there will be 18 $Cr_{2}O_{3}$ units in 1 unit cell.

Since, there are 2 Cr atoms and 3 oxygen atoms thus, units of chromium and oxygen will be 2×18=36 and 3×18=54 respectively.

The atomic radii of $Cr^{3+}$ and $O^{2-}$ is 62 pm and 140 pm respectively.

Converting them into cm:

$1 pm=10^{-10}cm$

Thus,

$r_{Cr^{3+}}=6.2\times 10^{-9}cm$

and,

$r_{O^{2-}}=1.4\times 10^{-8}cm$

Volume of sphere will be sum of volume of total number of cations and anions thus,

$V_{S}=V_{Cr^{3+}}+V_{O^{2-}}$

Since, volume of sphere is $V=\frac{4}{3}\pi r^{3}$ ,

$V_{S}=36\left ( \frac{4}{3}\pi (r_{Cr^{3+})^{3}} \right )+54\left ( \frac{4}{3}\pi (r_{O^{2-})^{3}} \right )$

Putting the values,

$V_{S}=36\left ( \frac{4}{3}(3.14) (6.2\times 10^{-9} cm)^{3}} \right )+54\left ( \frac{4}{3}(3.14) (1.4\times 10^{-8} cm)^{3}} \right )=6.6\times 10^{-22}\times 10^{-8}cm^{3}$

The atomic packing factor is ratio of volume of sphere and volume of crystal, thus,

$packing factor=\frac{V_{S}}{V_{C}}=\frac{6.6\times 10^{-22}cm^{3}}{8.7\times 10^{-22}cm^{3}}=0.758$

Thus, atomic packing factor is 0.758.

6 0

3 years ago

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When a nonmetal bonds with a nonmetal it is a _ bond

Karolina [17]

It is a covalent bond

3 0

3 years ago

The charge on an ion is known as its___number.

a_sh-v [17]

Answer:

oxidation number is correct!! :)

Explanation:

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3 years ago

What is the specific heat of titanium in j/(g⋅∘c) if it takes 89.7 j to raise the temperature of a 33.0 g block by 5.20 ∘c?

larisa [96]

Specific heat capacity is the amount of energy required to raise one gram of substances by 1 degree celsius . Therefore specific heat capacity for tatanium is 89.7j /( 33.0g x5.2 degree celsius) = 0.52j/g degree celcius
Molar mass for tatanium is 47.9 g/mole
heat is therefore 47.9 g/mole x 0.52j/g =24.9j/mole

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3 years ago

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