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3 years ago

What is the formula to use for this question, "how far does light travel in 2.5s"?

1 answer:

Nutka1998 [239]3 years ago

6 0

The definition of the speed of light is exactly 299,792,458 meters per second, so to find how far it travels in a time period, multiply the speed of light times the time. Aka c=299,792,458m/s where c is speed of light, m is meters, and s is seconds. So for example to find how far light travels in 5 seconds, multiply by 5.

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How many moles of helium gas are contained in a 4.0 L flask at STP

Ratling [72]

First, you convert liters to moles.
Usually you have to go to grams but this is STP.

Get moles directly by dividing the 4 by STP (22.4)
$\frac{4}{22.4} =0.17857142857$
About $1.8*10^{-1}$ or 0.18 moles whichever your teacher prefers

3 0

3 years ago

What is an element considered a pure substance?

Alona [7]

A compound is a pure substance composed of two or more different atoms chemically bonded to one another. A compound can be destroyed by chemical means. It might be broken down into simpler compounds, into its elements or a combination of the two.

8 0

3 years ago

Good morning, I have a question..

matrenka [14]

Answer:

<h3>The answer is 5.24 mL</h3>

Explanation:

The volume of a substance when given the density and mass can be found by using the formula

$volume = \frac{mass}{density} \\$

From the question

mass = 152 g

density = 29 g/cm³

We have

$volume = \frac{152}{29} \\ = 5.24137931...$

We have the final answer as

Hope this helps you

7 0

3 years ago

I NEED HELP PLEASE!!!! CHEMISTRY QUESTION: If 38 g of Li3P and 15 grams of Al2O3 are reacted, what total mass of products will r

maksim [4K]

Answer:

21.5 g.

Explanation:

Hello!

In this case, since the reaction between the given compounds is:

$2Li_3P+Al_2O_3\rightarrow 3Li_2O+2AlP$

We can see that according to the law of conservation of mass, which states that matter is neither created nor destroyed during a chemical reaction, the total mass of products equals the total mass of reactants based on the stoichiometric proportions; in such a way, we first need to compute the reacted moles of Li3P as shown below:

$n_{Li_3P}^{reacted}=38gLi_3P*\frac{1molLi_3P}{51.8gLi_3P}=0.73molLi_3P$

Now, the moles of Li3P consumed by 15 g of Al2O3:

$n_{Li_3P}^{consumed \ by \ Al_2O_3}=15gAl_2O_3*\frac{1molAl_2O_3}{101.96gAl_2O_3} *\frac{2molLi_3P}{1molAl_2O_3} =0.29molLi_3P$

Thus, we infer that just 0.29 moles of 0.73 react to form products; which means that the mass of formed products is:

$m_{Li_2O}=0.29molLi_3P*\frac{3molLi_2O}{2molLi_3P} *\frac{29.88gLi_2O}{1molLi_2O} =13gLi_2O\\\\m_{AlP}=0.29molLi_3P*\frac{2molAlP}{2molLi_3P} *\frac{57.95gAlP}{1molAlP} =8.5gAlP$

Therefore, the total mass of products is:

$m_{products}=13g+8.5g\\\\m_{products}=21.5g$

Which is not the same to the reactants (53 g) because there is an excess of Li₃P.

Best Regards!

7 0

3 years ago

A 0.1 gram sample of an unknown liquid is vaporized completely at 70 degrees C to fill a 750mL flask. The pressure is 0.05951atm

Deffense [45]

Answer:

The molar mass of the liquid 62.89 g/mol

Explanation:

Step 1: Data given

Mass of the sample = 0.1 grams

Temperature = 70°C

Volume = 750 mL

Pressure = 0.05951 atm

Step 2: Calculate the number of moles

p*V = n*R*T

n = (p*V)/(R*T)

⇒ with n = the number of moles gas = TO BE DETERMINED

⇒ with p = The pressure = 0.05951 atm

⇒ with V = The volume of the flask = 750 mL = 0.750 L

⇒ with R = The gasconstant = 0.08206 L*atm/K*mol

⇒with T = the temperature = 70 °C = 343 Kelvin

n = (0.05951 *0.750)/(0.08206*343)

n = 0.00159 moles

Step 3: Calculate molar mass

Molar mass = mass / moles

Molar mass =0.1 gram / 0.00159 moles

Molar mass = 62.89 g/mol

The molar mass of the liquid 62.89 g/mol

6 0

3 years ago