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Paladinen [302]

3 years ago

14

Potassium cyanide is a toxic substance, and the median lethal dose depends on the mass of the person or animal that ingests it.

The median lethal dose of KCN for a person weighing 145 lb (65.8 kg ) is 7.27 x 10^−3 mol .
1. What volume of a 0.0820 M KCN solution contains 7.27x 10^−3 mol of KCN?

1 answer:

Artemon [7]3 years ago

4 0

Answer:

88,7 mL of solution

Explanation:

Molarity (Represented as M) is an unit of chemical concentration that is defined as the ratio between moles of solute per liters of solution, that is:

Molarity = moles of solute / Liters of solution

If molarity of KCN solution is 0,0820M and moles of KCN are 7,27x10⁻³ moles:

0,0820M = 7,27x10⁻³ moles / Liters of solution

Liters of solution = 0,0887L = <em>88,7 mL of solution</em>

I hope it helps!

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Answer:

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2 years ago

How much energy is released by the decay of 3 grams of 230Th in the following reaction 230 Th - 226Ra + "He (230 Th = 229.9837 g

Serhud [2]

<u>Answer:</u> The energy released for the decay of 3 grams of 230-Thorium is $2.728\times 10^{-15}J$

<u>Explanation:</u>

First we have to calculate the mass defect $(\Delta m)$ .

The equation for the alpha decay of thorium nucleus follows:

$_{90}^{230}\textrm{Th}\rightarrow _{88}^{226}\textrm{Ra}+_2^{4}\textrm{He}$

To calculate the mass defect, we use the equation:

Mass defect = Sum of mass of product - Sum of mass of reactant

$\Delta m=(m_{Ra}+m_{He})-(m_{Th})$

$\Delta m=(225.9771+4.008)-(229.9837)=1.4\times 10^{-3}amu=2.324\times 10^{-30}kg$

(Conversion factor: $1amu=1.66\times 10^{-27}kg$ )

To calculate the energy released, we use Einstein equation, which is:

$E=\Delta mc^2$

$E=(2.324\times 10^{-30}kg)\times (3\times 10^8m/s)^2$

$E=2.0916\times 10^{-13}J$

The energy released for 230 grams of decay of thorium is $2.0916\times 10^{-13}J$

We need to calculate the energy released for the decay of 3 grams of thorium. By applying unitary method, we get:

As, 230 grams of Th release energy of = $2.0916\times 10^{-13}J$

Then, 3 grams of Th will release energy of = $\frac{2.0916\times 10^{-13}}{230}\times 3=2.728\times 10^{-15}J$

Hence, the energy released for the decay of 3 grams of 230-Thorium is $2.728\times 10^{-15}J$

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The average weather conditions affecting a biome is called ____.

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3 years ago

When 6.040 grams of a hydrocarbon, CxHy, were burned in a combustion analysis apparatus, 18.95 grams of CO2 and 7.759 grams of H

algol [13]

Answer: The empirical formula is $CH_2$ and molecular formula is $C_4H_8$

Explanation:

We are given:

Mass of $CO_2$ = 18.95 g

Mass of $H_2O$ = 7.759 g

Molar mass of carbon dioxide = 44 g/mol

Molar mass of water = 18 g/mol

For calculating the mass of carbon:

In 44g of carbon dioxide, 12 g of carbon is contained.

So, in 18.59 g of carbon dioxide, = $\frac{12}{44}\times 18.59=5.07g$ of carbon will be contained.

For calculating the mass of hydrogen:

In 18g of water, 2 g of hydrogen is contained.

So, in 7.759 g of water, = $\frac{2}{18}\times 7.759=0.862g$ of hydrogen will be contained.

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Mass of H = 0.862 g

Step 1 : convert given masses into moles.

Moles of C = $\frac{\text{ given mass of C}}{\text{ molar mass of C}}= \frac{5.07g}{12g/mole}=0.422moles$

Moles of H= $\frac{\text{ given mass of H}}{\text{ molar mass of H}}= \frac{0.862g}{1g/mole}=0.862moles$

Step 2 : For the mole ratio, divide each value of moles by the smallest number of moles calculated.

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For H = $\frac{0.862}{0.422}=2$

The ratio of C : H = 1: 2

Hence the empirical formula is $CH_2$ .

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The molecular weight = 56.1 g/mole

Now we have to calculate the molecular formula.

$n=\frac{\text{Molecular weight }}{\text{Equivalent weight}}=\frac{56.1}{14}=4$

The molecular formula will be= $4\times CH_2=C_4H_8$

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2 years ago