How do experiments help scientists learn about the world?

A reaction produced 37.5 L of oxygen gas at 307 K and 1.25 atm. How many moles of oxygen were produced? 0.538 mol, O2 1.86 mol,

zlopas [31]

Answer:

O 2 has a mass of 1.78g

Explanation:

We are at STP and that means we have to use the ideal gas law equation!

P represents pressure (could have units of atm, depending on the units of the universal gas constant)

V represents volume (must have units of liters)

n represents the number of moles

R is the universal gas constant (has units of

L

× a t m

m o l

×

K

)

T represents the temperature, which must be in Kelvins.

Next, list your known and unknown variables. Our only unknown is the number of moles of

O

2

(

g

)

. Our known variables are P,V,R, and T.

At STP, the temperature is 273K and the pressure is 1 atm. The proportionality constant, R, is equal to 0.0821

L

×

a

t

m

o

l

×

K

Now we have to rearrange the equation to solve for n

n

=

P

V

R

T

n

=

1

atm

×

1.25

L

0.0821

Lxxatm

m

o

l

×

K

×

273

K

n

=

0.05577

m

o

l

To get the mass of

O

2

, we just have to use the molar mass of oxygen as a conversion factor:

0.0577

mol

O

2

×

32.00

g

1

mol

= 1.78g

O

2

3 0

3 years ago

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Given the initial rate data for the reaction being A + B + C --> D determine the rate expression for the reaction and the (k)

Vesnalui [34]

Answer:

k = 100 mol⁻² L² s⁻¹, r= k[A][B]²

Explanation:

A + B + C --> D

[A] [B] [C] IRR

0.20 0.10 0.40 .20

0.40 0.20 0.20 1.60

0.20 0.10 0.20 .20

0.20 0.20 0.20 .80

Comparing the third and fourth reaction, the concentrations of A and C are constant. Doubling the concentration of B causes a change in the rate of the reaction by a factor of 4.

This means the rate of reaction is second order with respect to B.

Comparing reactions 2 and 3, the concentrations of B and C are constant. Halving the concentration of A causes a change in the rate of the reaction by a factor of 2.

This means the rate of reaction is first order with respect to A.

Comparing reactions 1 and 3, the concentrations of A and B are constant. Halving the concentration of A causes no change in the rate of the reaction.

This means the rate of reaction is zero order with respect to C.

The rate expression for this reaction is given as;

r = k [A]¹[B]²[C]⁰

r= k[A][B]²

In order to obtain the value of the rate constant, let's work with the first reaction.

r = 0.20

[A] = 0.20 [B] = 0.10

k = r / [A][B]²

k = 0.20 / (0.20)(0.10)²

k = 100 mol⁻² L² s⁻¹

8 0

4 years ago

The average cup of coffee contains about 125 mg of caffeine, C3H10N402. Caffeine is also found in tea, colas, and headache remed

slavikrds [6]

Answer:

ten atoms of hydrogen are present in one mole of caffeine.

Explanation:

Molecular formula of caffiene is given which is C3H10N4O2. It clearly shows that ten atoms of hydrogen are present. One mole is amount equal to one molecular weight of a molecule which is derived from molecular formula. So as moecular formula has ten atoms of hydrogen, one mole of caffeine has 10 atoms of hydrogen.

8 0

4 years ago

a gap in the rock layer due to erosion from no rocks being deposited.HELP FAST PLEASE!?!?!?!?

Allushta [10]

a gap in the rock layer due to erosion or from no rocks being deposited

geological processes taking place today are the same as those that occurred in the past.

fossil that record the shape and structure of an organism

each layer is older than the layer above and younger than the layer below it.

the preserved remains or traces of a once living organism.

fossils that record the movement or behavior of an organism.

sediments spread in all directions until they thin out or hit a barrier.

sedimentary rocks are deposited horizontally.

age of rock compared to the ages of rock layers.

age of rocks calculated in years since formed.

words:

1.absolute age

2.body fossil

3.fossil

4.principle of lateral continuity

5.principle of original horizontally

6.principle of superposition

7.relative age

8.trace fossil

9. unconformity

10.uniformitarianism

Answer is 9,10,2,6,3,8,4,5,7,1

All my answers were correct on this one

6 0

4 years ago

Which molecule is amphoteric? A) NH4+ B )H2O C )H2CO3− D )H2SO4

Maslowich

The answer is letter choice B

4 0

4 years ago

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