At STP, how many moles are in 0.880L of He gas?

Aluminum–lithium (Al–Li) alloys have been developed by the aircraft industry to reduce the weight and improve the performance of

gtnhenbr [62]

Answer:

The concentration of Li (in wt%) is 3,47g/mol

Explanation:

To obtain the 2,42g/cm³ of density:

2,42g/cm³ = 2,71g/cm³X + 0,534g/cm³Y (1)

Where X is molar fraction of Al and Y is molar fraction of Li.

X + Y = 1 (2)

Replacing (2) in (1):

Y = 0,13

Thus, X = 0,87

The weight of Al and Li is:

0,87*26,98g/mol = 23,4726 g of aluminium

0,13*6,941g/mol = 0,84383 g of lithium

The concentration of Li (in wt%) is:

0,84383g/(0,84383g+23,4726g) ×100= 3,47%

6 0

2 years ago

The first step in the Ostwald process for producing nitric acid is 4NH3(g) + 5O2(g) --> 4NO(g) + 6H2O(g). If the reaction of

wel

Answer:

a. 77%

Explanation:

To solve the exercise, you need to know the limiting reagent. The limiting reagent is one that is consumed first in the chemical reaction. The other reagent is known as an excess reagent, and it is the one left over in a chemical reaction.

To know if ammonia or oxygen is the limiting reagent, we should relate the weights of both compounds in the reaction. We know that 4NH3 (68 g) react with 5O2 (160 g), so we should find out how much NH3 is required to react with 150 g of O2:

160 g O2 _______ 68 g NH3

150 g O2 _______ x = 150 g * 68 g / 160 g = 63.75 g NH3

As we have 150 g of NH3 but only 63.75 g are required, we know that ammonia is the excess reagent, so oxygen is the reagent that limits the reaction and that we should use to calculate the percentage yield of the reaction.

In the reaction we observe that 5O2 (160 g) produces 4NO (120g), so:

160 g O2 ______ 120 g NO

150 g O2 ______ x = 150 g * 120 g / 160 g = 112.5 g NO

If the percent yield of the reaction were 100%, it would produce 112.5 g of NO, however only 87 g of NO were obtained, so we should find out what the percentage of reaction yield was:

112.5 g NO ______ 100%

87 g NO _______ x = 87g * 100% / 112.5 g = 77%

Thus we observe that the reaction had a yield of 77%.

7 0

2 years ago

Read 2 more answers

Consider 2.4 moles of a gas contained in a 4.0 L bulb at a constant temperature of 32°C. This bulb is connected to an evacuated

Luden [163]

Complete Question

The complete question is shown on the first uploaded image

Answer

a

As the valve is opened , the gas will flow into the empty container until the both containers have the same pressure

b

$\Delta H = 0\ , \Delta E = 0 , q= 0 , w= 0$

c

The driving force for this process is the increase in entropy this is because the movement of the internal energy of the gas into a larger volume, what this does is that it increases the amount of disorder(entropy).

Explanation

In order to obtain the parameter in the part B of the question we are first obtain the initial pressure, using the ideal gas equation

$P = \frac{nRT}{V}$

$P = \frac{(2.4mol)(0.0821\frac{1 atm}{K \cdot \ mol} )}{4.0L}$

$P =15 \ atm$

The next thing is to obtain the new pressure of the gas , using boyle's law

$P_1V_1 = P_2V_2$

$P_2 = \frac{P_1 V_1}{V_2}$

$P_2 = \frac{(15 \ atm)(4.0L)}{24.0 L}$

$P_2 = 2.5 \ atm$

Since the this process is isothermal , the change in heat is equal to zero

i.e q = 0 J

The workdone to move the gas to the other container is zero because the the pressure at this second container is zero due to the fact that it is a vacuum

i.e $w = -P_{external} \Delta V$

$=-(0 \ atm) (24.0 - 4.0L)$

$= 0L \cdot atm$

Since the change in heat is zero and the workdone is zero then the change in internal energy is equal to 0

This is because the change in internal energy is equal to a summation of change in heat and the workdone

i.e $\Delta E = q + w$

$= 0J$

Generally the change in enthalpy is mathematically represented as

$\Delta H = n C_p \Delta T$

Since the temperature is zero this means that the change in temperature is zero , substituting this value for change in temperature into the equation for change in enthalpy

$\Delta H = n C_p (0)$

$= 0J$

7 0

2 years ago

Label each statement with its corresponding type of scientific knowledge. law theory fact hypothesis The melting point of ice is

EleoNora [17]

Answer:

Follows are the solution to this question:

Explanation:

Fact: In this, the ice is melted at 0 ° C.
law: It is used to repeated experiments consistently showed which objects marked to both the contrary attract each law.
Hypothesis: If carbohydrates and nitrogen are combined at 1500 ° C, they interact with one another.
Theory: Protons, nuclei, or ions are made of Atoms. As these molecules could not be seen explicitly, such legal structure several experimental observations.

3 0

2 years ago

Microwave ovens are able to cook food because they increase the_______ of water molecules in the food.

Whitepunk [10]

potential energy with the heat given to the food

4 0

2 years ago