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3 years ago

Which of the following is not one of the three categories of mechanicalwaves?

Chemistry

1 answer:

solong [7]3 years ago

8 0

Answer:

d. Radio wave

Explanation:

There are three types of mechanical waves, transverse waves, longitudinal waves, and surface waves

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Is the statement correct or incorrect? Explain. A) It is correct. The ashes weigh less than the original wood and this proves th

Vladimir79 [104]

The correct answer is D

According to the law of conservation of mass, mass can not be destroyed or lost, it can just be rearranged in space, turned into energy etc.

Therefore, in our of example the wood was burned and turned into ashes. Even though the ashes weight less than the original wood, some of the solid mass of the wood was converted to gas and energy, so the overall mass remained the same.

7 0

3 years ago

A sample of gas has a mass of 38.8 mg. Its volume is 224 mL at a temperature of 55 °C and a pressure of 886 torr. Find the molar

Pie

Answer:

4g/mol

Explanation:

Firstly, we can get the number of moles of the gas present using the ideal gas equation.

PV = nRT

Here:

P = 886 torr

V = 224ml = 224/1000 = 0.224L

T = 55 degrees celcius= 55+ 273.15 = 328.15K

R = molar gas constant = 62.36 L⋅Torr⋅K−1⋅mol−1

n = PV/RT

n = (886 * 0.224)/(62.36 * 328.15)

n = 0.009698469964 mole

Now to get the molar mass, this is mathematically equal to the mass divided by the number of moles. We have the mass and the number of moles, remaining only the molar mass.

First, we convert the mass to g and that is 38.8/1000 = 0.0388

The molar mass is thus 0.0388/0.009698469964 = 4g/mol

3 0

4 years ago

Tell how many moles of each element are in the following amounts of each compound

qwelly [4]

Take note of the subscript written for each element in the compound. To find the total number of moles, make sure to multiply the subscript with the number of moles of compound. The answer for each is written below:

a. 3*1 = 3 moles Nitrogen; 3*3 = 9 moles Hydrogen
b. 0.25*2 = 0.5 moles Hydrogen; 0.25*1 = 0.25 moles Oxygen
c. 5*2 = 10 moles Hydrogen; 5*1 =5 moles Sulfur; 5*4 = 20 moles Oxygen
d. 0.75*1 = 0.75 moles Calcium; 0.75*1*2 = 1.5 moles Nitrogen; 0.75*3*2 = 4.5 moles Oxygen

7 0

3 years ago

Hydrazine, , emits a large quantity of energy when it reacts with oxygen, which has led to hydrazine used as a fuel for rockets:

Tcecarenko [31]

Answer:

$1.25~mol~H_2O$ and $0.627~mol~N_2$

Explanation:

Our goal for this question is the calculation of the number of moles of the molecules produced by the reaction of hydrazine ( $N_2H_4$ ) and oxygen ( $O_2$ ). So, we can start with the reaction between these compounds:

$N_2H_4~+~O_2~->~N_2~+~H_2O$

Now we can balance the reaction:

$N_2H_4~+~O_2~->~N_2~+~2H_2O$

In the problem, we have the values for both reagents. Therefore we have to calculate the limiting reagent. Our first step, is to calculate the moles of each compound using the molar masses values (32.04 g/mol for $N_2H_4$ and 31.99 g/mol for $O_2$ ):

$20.1~g~N_2H_4\frac{1~mol~N_2H_4}{32.04~g~N_2H_4}=0.627~mol~N_2H_4$

$20.1~g~O_2\frac{1~mol~O_2}{31.99~g~O_2}=0.628~mol~O_2$

In the balanced reaction we have 1 mol for each reagent (the numbers in front of $O_2$ and $N_2H_4$ are 1). Therefore the smallest value would be the limiting reagent, in this case, the limiting reagent is $N_2H_4$ .

With this in mind, we can calculate the number of moles for each product. In the case of $N_2$ we have a 1:1 molar ratio (1 mol of $N_2$ is produced by 1 mol of $N_2H_4$ ), so:

$0.627~mol~N_2H_4\frac{1~mol~N_2}{1~mol~N_2H_4}=~0.627~mol~N_2$

We can follow the same logic for the other compound. In the case of $H_2O$ we have a 1:2 molar ratio (2 mol of $H_2O$ is produced by 1 mol of $N_2H_4$ ), so: