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1 year ago

What is the mass of 2.15 liters of N2 gas at STP?

Chemistry

1 answer:

devlian [24]1 year ago

6 0

Answer:

2.68g

Explanation:

Given parameters:

Volume of gas at STP = 2.15L

Unkown:

Mass of Nitrogen N₂ gas at STP = ?

Solution

To find the mass of the gas at STP, we use the mole concept approach.

In using the mole approach we follow the following procedures:

1. Find the number of moles of gas at STP using the relationship below:

Number of moles = $\frac{volume occupied}{22.4dm^{3} mol^{-1} }$

Note: 1L = 1dm³

2. Then using the mole and mass relationship, we can find the mass of the gas using the equation below:

Mass = number of moles x molar mass

Workings

1. Number of moles of N₂ = $\frac{2.15}{22.4}$

Number of moles of N₂ = 0.096mole

2. Given that the atomic mass of N = 14g

Molar mass of N₂ = 2 x 14 = 28gmol⁻¹

Mass = 0.096mol x 28gmol⁻¹ = 2.68g

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How many Ca2+ ions are in a sample of CaSO4 having a total mass of 68.07 g?

harkovskaia [24]

Answer:

There are

17.01

Explanation:

The chemical formula for calcium phosphate is

(PO

)

. This means that in one mole of calcium phosphate, there are three calcium ions and two phosphate ions.

6 0

1 year ago

Reserpine is a natural product isolated from the roots of the shrub Rauwolfia serpentina. It was first synthesized in 1956 by No

liraira [26]

Answer:

Molality = 0.066 m

Molar mass = 608.36 g/mol

Explanation:

It seems the question is incomplete. However a web search us shows this data:

" Reserpine is a natural product isolated from the roots of the shrub Rauwolfia serpentina. It was first synthesized in 1956 by Nobel Prize winner R. B. Woodward. It is used as a tranquilizer and sedative. When 1.00 g reserpine is dissolved in 25.0 g camphor, the freezing-point depression is 2.63 °C (Kf for camphor is 40 °C·kg/mol). Calculate the molality of the solution and the molar mass of reserpine. "

The freezing-point depression is expressed by:

ΔT=Kf * m

We put the data given by the problem and solve for m:

2.63 °C = 40°C·kg/mol * m

m = 0.06575 m

For the calculation of the molar mass: Molality is defined as moles of solute per kilogram of solvent:

0.06575 m = Moles reserpine / kg camphor

25.0 g camphor ⇒ 25.0/1000 = 0.025 kg camphor

We calculate moles of reserpine:

0.06575 m = Moles reserpine / 0.025 kg camphor

Moles reserpine = 1.64x10⁻³ mol

Finally we use the mass of reserpine and the moles to calculate the molar mass:

1.00 g reserpine / 1.64x10⁻³ mol = 608.36 g/mol

Keep in mind that if the data in your problem is different, the results will be different. But the solving method remains the same.

8 0

2 years ago

Zinc is to be electroplated onto both sides of an iron sheet that is 20 cm2 as a galvanized sacrificial anode. It is desired to

Alexandra [31]

Answer:

The time required for the coating is 105 s

Explanation:

Zinc undergoes reduction reaction and absorbs two (2) electron ions.

The expression for the mass change at electrode $(m_{ch})$ is given as :

$\frac{m_{ch}}{M} ZF = It$

where;

M = molar mass

Z = ions charge at electrodes

F = Faraday's constant

I = current

A = area

t = time

also; $(m_{ch})$ = $(Ad) \rho$ ; replacing that into above equation; we have:

$\frac{(Ad) \rho}{M} ZF = It$ ---- equation (1)

where;

A = area

d = thickness

$\rho$ = density

From the above equation (1); The time required for coating can be calculated as;

$[ \frac{20 cm^2 *0.0025 cm*7.13g/cm^3}{65.38g/mol}*2 \frac{moles\ of \ electrons}{mole \ of \ Zn} * 9.65*10^4 \frac{C}{mole \ of \ electrons } ] = (20 A) t$