Are these sentences true or false? Tick the boxes

Which sample of gas at STP has the same number of molecules as 6 liters of Cl2(g) at STP?

lara [203]

Answer:

The correct answer is option 2 (6 liters of N2)

Explanation:

The complete question

Which sample of gas at STP has the same number of molecules as 6 liters of Cl2(g) at STP?

(1) 3 liters of O2(g)

(2) 6 liters of N2(g)

(3) 3 moles of O2(g)

(4) 6 moles of N2(g)

Step 1: Data given

Volume = 6 L

STP = 1 atm and 273 K

Step 2: Calculate moles of Cl2

p*V = n*R*T

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

⇒with n = the number of moles Cl2 = TO BE DETERMINED

⇒with V = the volume of Cl2 = 6.0 L

⇒with p = the pressure of Cl2 = 1 atm

⇒with R = the gas constant = 0.08206 L*atm/mol*K

⇒ with T = the temperature = 273 K

n = (1.0 * 6.0 ) (0.08206 * 273)

n = 0.2678 moles Cl2

This means we need 0.2678 moles of a gas at STP

Option 3 has 3 moles of O2 ⇒ Not the same number of molecules

Option 4 has 6 moles of N2 ⇒ Not the same number of molecules

For 3 liters of O2 we'll have:

⇒with n = the number of moles O2 = TO BE DETERMINED

⇒with V = the volume of O2 = 3.0 L

⇒with p = the pressure of O2 = 1 atm

⇒with R = the gas constant = 0.08206 L*atm/mol*K

⇒ with T = the temperature = 273 K

n = (1.0 * 3.0 ) (0.08206 * 273)

n = 0,1339 moles ⇒ Not the same number of molecules

For 6 liters of N2 we'll have

⇒with n = the number of moles N2 = TO BE DETERMINED

⇒with V = the volume of N2 = 6.0 L

⇒with p = the pressure of N2 = 1 atm

⇒with R = the gas constant = 0.08206 L*atm/mol*K

⇒ with T = the temperature = 273 K

n = (1.0 * 6.0 ) (0.08206 * 273)

n = 0.2678 moles N2 ⇒ The same number of molecules

The correct answer is option 2 (6 liters of N2)

3 0

3 years ago

Explain how you can determine from the periodic table exactly how many neutrons are in an atom?

Ronch [10]

Answer:

The numbers in the corner

Explanation:

Using the numbers in the corner, we know that they will tell us the number of neutrons, thus forth answering your question.

5 0

3 years ago

A 1.000 gram sample of the rocket fuel hydrazine (N2H4) is burned in a bomb calorimeter. The temperature rises from 24.62°C to 2

Dominik [7]

Answer:

The molar heat of combustion of hydrazine is -663.82 kJ/mole.

Explanation:

First we have to calculate the heat gained by the calorimeter.

$q=c\times (T_{final}-T_{initial})$

where,

q = heat gained = ?

c = specific heat = $5860 J/^oC$

$T_{final}$ = final temperature = $28.16^oC$

$T_{initial}$ = initial temperature = $24.62^oC$

Now put all the given values in the above formula, we get:

$q=5860 J/^oC\times (28.16-24.62)^oC$

$q=20,744.4 J=20.7444 kJ$

Now we have to calculate the enthalpy change during the reaction.

$\Delta H=-\frac{q}{n}$

where,

$\Delta H$ = enthalpy change = ?

q = heat gained = 20.7444 kJ

n = number of moles fructose = $\frac{\text{Mass of hydrazine}}{\text{Molar mass of hydrazine}}=\frac{1.000 g}{32 g/mol}=0.03125 mole$

$\Delta H=-\frac{20.7444 kJ}{0.03125 mole}=-663.82 kJ/mole$

The molar heat of combustion of hydrazine is -663.82 kJ/mole.

4 0

3 years ago

If 1.02 g of nickel reacted with 750. mL of 0.112 M hydrobromic acid, how much of each will be present at the end of the reactio

kati45 [8]

Answer:

35.1% is percent yield

Explanation:

Full question: Assume no volume change. If you formed 0.0910 atm of gas, what is the percent yield?

The reaction that is occurring is:

Ni + 3HBr → NiBr₃ + 3/2H₂(g)

First, we will determine moles of Ni and HBr to determine limiting reactant and theoretical yield

Using ideal gas law, we can determine the moles of hydrogen formed. Thus, we can find percent yield:

Moles Ni (Molar mass: 58.69g/mol):

1.02g * (1mol / 58.69g) = 0.01738moles Ni

Moles HBr:

0.750L * (0.112mol/L) = 0.084 moles of HBr.

For a complete reaction of the 0.084 moles of HBr you need:

0.084mol HBr * (1 mole Ni / 3 moles HBr) = 0.028 moles of Ni.

As there are just 0.01738 moles of Ni, the Ni is limiting reactant. Assuming a theoretical yield, moles of H₂ produced are:

0.01738moles Ni * (3/2 H₂ / 1 mol Ni) = 0.02607 moles H₂

Now, moles of H₂ produced are:

PV = nRT

PV/RT = n

Where P is pressure (0.0910atm)

V is volume (2.50L)

R is gas constant (0.082atmL/molK)

T is absolute temperature in Kelvin (30°C + 273.15 = 303.15K)

And n are moles

PV/RT = n

0.0910atm*2.50L/0.082atmL/molK*303.15K = n

0.00915 moles = n

And percent yield (Produced moles / Theoretical moles * 100) is:

0.00915 moles / 0.02607moles =

<h3>35.1% is percent yield</h3>

8 0

3 years ago

Which of the following symbol means a subtance is in water solutions?

tankabanditka [31]

Answer:

a.) (aq)

Explanation:

(aq) means aqueous

so its in a solvent

7 0

2 years ago