Round off 35.65 to three significant figures. help

How many liters of oxygen gas can react with 84.0 grams of lithium metal at standard temperature and pressure? Show all of the w

ddd [48]

From the equation:
4mol Li react with 1 mol O2
Molar mass Li = 7g/mol
mol in 84g Li = 84/7 = 12 mol Li
From the equation - 12 mol Li will react with 3 mol O2

At STP 1 mol O2 has volume = 22.4L
 At STP 3 mol O2 has volume = 3*22.4 = 67.2L O2 gas will react.

5 0

2 years ago

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SOMEONE HELP ASAPP...

saveliy_v [14]

AnswU GOT THIS!!!!!!!!!!!!!

Explanation:

4 0

3 years ago

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A student collects 350 mL of a vapor at a temperature of 67°C. The atmospheric pressure at the time of collection is 0.900 atm.

Fed [463]

Answer:

Explanation:

This problem is very similar to the other that you put before, so, we'll use the same principle here.

The ideal gas equation: PV = nRT

Where:

P: pressure in atm

V: volume in L

T: Temperature in K.

n: moles

R: Gas constant (In this case, we'll use 0.082 L atm/K)

to get the molar mass of the gas, we need to know the moles, and with the mass, we can know the molar mass. However we can put the ideal gas expression with the molar mass in this way:

we know that n is mole so:

n = g/MM

If we put this in the idea gases expression we have:

PV = gRT/MM

Solving for MM we have:

MM = gRT/PV

Now, let's convert the temperature and volume to K and L respectively:

T = 67 + 273 = 340 K

V = 350 / 1000 = 0.35 L

Now all we have to do is put all the data into the expression:

MM = 0.79 * 0.082 * 340 / 0.9 * 0.35

MM = 22.0252 / 0.315 = 69.92 g/mol rounded 70 g/mol

Now, the closest answer of your options would be 72 g/mol. This could be easily explained because we do not use all the significant figures of all numbers, including the gas constant of R. However, all the work, calculations and procedure is correct and fine, and we only have a minimum range of 2 units.

6 0

3 years ago

To indicate the pH of a substance, one can use a dye that is both an acid and that appears as different colors in its protonated

PIT_PIT [208]

Answer:

The pH of the solution is 7.8

Explanation:

The concentration of the solution is 0.001M and the dye could be in its protonated and deprotonated forms. If the concentration of the protonated form [HA] is 0.0002 M the concentration of the deprotonated form will be the subtraction between the concentration of the bye and the concentration of the protonated form:

[A-] = 0.001M - 0.0002M = 0.0008M

Also, the Henderson-Hasselbalch equation is

$pH = pKa + Log \frac{[A^{-}]}{[HA]}$

this equation shows the dependency between the pH of the solution, the pKa and the concentration of the protonated and deprotonated forms. Thus, replacing in the equation

$pH = 7.2 + Log \frac{0.0008M}{0.0002M} = 7.8$

3 0

3 years ago

What is the atomic number of the as yet undiscovered element in which the 8s and 8p electron energy levels?

Andreyy89

The atomic number of the undiscovered element is 168

Element 118 will have just filled its 7p orbitals. therefore the predicted element to fill completely up to its 8 p orbital would have to filled a whole set of s, p, d, f and g orbitals

That's another 2 + 6 + 10 +14 + 18 = 50 electrons

To determine the total number of quantum numbers we have to find

Nml × Nms

we have Nml × Nms = ( 2 + 1 ) × 2

8s + 8P + 7d + 6f + 5g = 2 + 6 + 10 + 14 + 18 = 50

The element right below should be

Z = 118 + 50

= 168

Hence the atomic number of the undiscovered element is 168

Learn more about the atomic number on

brainly.com/question/14514242

#SPJ4

4 0

9 months ago