2 years ago

Is Helium a compound,element, or.mixture

Chemistry

1 answer:

dusya [7]2 years ago

5 0

Answer:

element

Explanation:

we know that helium is a pure substance although helium atoms are sometimes mixed with their isotopes it is still the same element. since there is no other element combined with helium this makes it an element.

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If 10.7 grams of NH4Cl is dissolved in enough water to make 800 mL of solution,what will be it's molarity

olga nikolaevna [1]

<h3><u>Answer;</u></h3>

Molarity = 0.25 M

<h3><u>Explanation;</u></h3>

Molarity is given by moles/Liter.

First we find moles:

Number of moles = Mass /molar mass

= (10.7g NH4Cl)/(53.5g/mol NH4Cl)

= 0.200 moles NH4Cl

Then we convert to liters:

= (800mL)*(1L/1000mL) = 0.800L

Therefore; molarity = 0.2moles/0.8L

= 0.25M

6 0

2 years ago

if the percent by volume is 2% and the volume of solution is 250 mL what is the volume of solute and solution

Liula [17]

Answer:

Solute = 5 mL; solution = 250 mL

Explanation:

The formula for percent by volume is

$\text{Percent by volume} = \dfrac{\text{Volume of solute}}{\text{Volume of solution}}\times 100 \, \%$

If you have 250 mL of a solution that is 2 % v/v,

$\begin{array}{rcl}2 \, \% & = & \dfrac{\text{Volume of solute}}{\text{250 mL}}\times 100 \, \%\\\\2 \times \text{ 250 mL} & = & \text{Volume of solute} \times 100\\\text{Volume of solute} & = & \dfrac{2 \times 250\text{ mL}}{100}\\\\ & = & \textbf{5 mL}\\\end{array}$