Can someone pls help me with this question

Chemistry

1 answer:

artcher [175]3 years ago

5 0

Answer:

The answer to your question is 24.325

Explanation:

Data

Magnesium-24 Abundance = 78.70%

Magnesium-25 Abundance = 10.13%

Magnesium-26 Abundance = 11.17%

Process

1.- Convert the abundance to decimals

Magnesium-24 Abundance = 78.70/100 = 0.787

Magnesium-25 Abundance = 10.13/100 = 0.1013

Magnesium-26 Abundance = 11.17/100 = 0.1117

2.- Write an equation

Average atomic mass = (Atomic mass-1 x Abundance 1) + (Atomic mass 2 x

Abundance-2) + (Atomic mass 3 x Abundance 3)

3.- Substitution

Average atomic mass = (24 x 0.787) + (25 x 0.1013) + (26 x 0.1117)

4.- Simplification

Average atomic mass = 18.888 + 2.533 + 2.904

5.- Result

Average atomic mass = 24.325

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If you are given the molarity of a solution, what additional information would you need to find the weight/weight percent (w/w%)

Ludmilka [50]

Answer:

- The molar mass of the solute, in order to convert from moles of solute to grams of solute.

- The density of solution, to convert from volume of solution to mass of solution.

Explanation:

Hello,

In this case, since molarity is mathematically defined as the moles of solute divided by the volume of solution and the weight/weight percent as the mass of solute divided by the mass of solution, we need:

- The molar mass of the solute, in order to convert from moles of solute to grams of solute.

- The density of solution, to convert from volume of solution to mass of solution.

For instance, if a 1-M solution of HCl has a density of 1.125 g/mL, we can compute the w/w% as follows:

$w/w\%=1\frac{molHCl}{L\ sln}*\frac{36.45gHCl}{1molHCl}*\frac{1L\ sln}{1000mL\ sln}*\frac{1mL\ sln}{1.125g\ sln} *100\%\\\\w/w\%=3.15\%$

Whereas the first factor corresponds to the molar mass of HCl, the second one the conversion from L to mL of solution and the third one the density to express in terms of grams of solution.

Regards.

4 0

3 years ago

A gas evolved during the fermentation of alcohol had a volume of 19.4 L at 17 °C and 746 mmHg. How many moles of gas were collec

AlexFokin [52]

Answer:- 0.800 moles of the gas were collected.

Solution:- Volume, temperature and pressure is given for the gas and asks to calculate the moles of the gas.

It is an ideal gas law based problem. Ideal gas law equation is used to solve this. The equation is:

PV=nRT

Since it asks to calculate the moles that is n, so let's rearrange this for n:

$n=\frac{PV}{RT}$