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Inessa [10]
3 years ago
15

In which era did the first fish appear?

Chemistry
1 answer:
VARVARA [1.3K]3 years ago
5 0
C Because Mesozoic Is An Era The First Fish Seen
You might be interested in
How many phosphate bonds are responsible for the high energy content of ATP?
Nataly_w [17]
The answer is a. one. There are three phosphate bonds in the ATP but only the first bond is responsible for the high energy. When this bond break, ATP will change to ADP.
4 0
3 years ago
Read 2 more answers
If a gas sample has a pressure of 30.7 kPa at 0.00*C, by how much does the temperature have to decrease to lower the pressure to
Scrat [10]

Answer:

                      252.68 K  or   -20.46 °C

Explanation:

                    According to Gay-Lussac's Law, "Pressure and Temperature at given volume are directly proportional to each other".

Mathematically,

                                              P₁ / T₁  =  P₂ / T₂   ---- (1)

Data Given:

                  P₁  =  30.7 kPa

                  T₁  =  0.00 °C  =  273.15 K

                  P₂  =  28.4 kPa

                  T₂  =  <u>???</u>

Solving equation for T₂,

                  T₂  =  P₂ T₁ / P₁

Putting values,

                  T₂  =  28.4 kPa × 273.15 K / 30.7 kPa

                  T₂  =  252.68 K  or   -20.46 °C

8 0
3 years ago
If an ice cube weighing 25.0 g with an initial
riadik2000 [5.3K]

Answer:

11

∘

C

Explanation:

As far as solving this problem goes, it is very important that you do not forget to account for the phase change underwent by the solid water at

0

∘

C

to liquid at

0

∘

C

.

The heat needed to melt the solid at its melting point will come from the warmer water sample. This means that you have

q

1

+

q

2

=

−

q

3

(

1

)

, where

q

1

- the heat absorbed by the solid at

0

∘

C

q

2

- the heat absorbed by the liquid at

0

∘

C

q

3

- the heat lost by the warmer water sample

The two equations that you will use are

q

=

m

⋅

c

⋅

Δ

T

, where

q

- heat absorbed/lost

m

- the mass of the sample

c

- the specific heat of water, equal to

4.18

J

g

∘

C

Δ

T

- the change in temperature, defined as final temperature minus initial temperature

and

q

=

n

⋅

Δ

H

fus

, where

q

- heat absorbed

n

- the number of moles of water

Δ

H

fus

- the molar heat of fusion of water, equal to

6.01 kJ/mol

Use water's molar mass to find how many moles of water you have in the

100.0-g

sample

100.0

g

⋅

1 mole H

2

O

18.015

g

=

5.551 moles H

2

O

So, how much heat is needed to allow the sample to go from solid at

0

∘

C

to liquid at

0

∘

C

?

q

1

=

5.551

moles

⋅

6.01

kJ

mole

=

33.36 kJ

This means that equation

(

1

)

becomes

33.36 kJ

+

q

2

=

−

q

3

The minus sign for

q

3

is used because heat lost carries a negative sign.

So, if

T

f

is the final temperature of the water, you can say that

33.36 kJ

+

m

sample

⋅

c

⋅

Δ

T

sample

=

−

m

water

⋅

c

⋅

Δ

T

water

More specifically, you have

33.36 kJ

+

100.0

g

⋅

4.18

J

g

∘

C

⋅

(

T

f

−

0

)

∘

C

=

−

650

g

⋅

4.18

J

g

∘

C

⋅

(

T

f

−

25

)

∘

C

33.36 kJ

+

418 J

⋅

(

T

f

−

0

)

=

−

2717 J

⋅

(

T

f

−

25

)

Convert the joules to kilojoules to get

33.36

kJ

+

0.418

kJ

⋅

T

f

=

−

2.717

kJ

⋅

(

T

f

−

25

)

This is equivalent to

0.418

⋅

T

f

+

2.717

⋅

T

f

=

67.925

−

33.36

T

f

=

34.565

0.418

+

2.717

=

11.026

∘

C

Rounded to two sig figs, the number of sig figs you have for the mass of warmer water, the answer will be

T

f

=

11

∘

C

Explanation:

3 0
2 years ago
What is the chemical equation for boiling a egg?
Nostrana [21]
Because an egg is an entire biological structure, made up of a mixture of chemicals rather than a single pure chemical compound, there is no one chemical formula to describe it. However, the basic structure and chemistry of an egg is highly conserved and varies little from species to species.
6 0
3 years ago
A 48.3 mL sample of gas in a cylinder is warmed from 22 °C to
goldenfox [79]

Answer:

58.94 mL

Explanation:

V1 = 48.3 mL             V2 = v mL

T1 = 22 degree celsius OR 295 k         T2 = 87 degree celsius OR 360 k

We will use the gas equation:

PV = nRT

Since the Pressure (p) , number of moles (n) and the universal gas constant(R) are all constants in this given scenario,

we can say that

V / T = k , (where k is a constant)

Since this is the first case,

V1 / T1 = k --------------------(1)

For case 2:

Since we have the same constants, the equation will be the same

V / T = k (where k is the same constant from before)

V2 / T2 = k (Since this is the second case) ------------------(2)

From (1) and (2):

V1 / T1 = V2 / T2

Now, replacing the variables with the given values

48.3 / 295 = v / 360

v = 48.3*360 / 295

v = 58.94 mL

Therefore, the final volume of the gas is 58.94 mL

4 0
3 years ago
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