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3 years ago

What is the minimum amount of heat required to completely melt 40.0 grams of ice at its melting point?

Chemistry

1 answer:

elena55 [62]3 years ago

6 0

If 20.0 grams of ice takes about 6680j...then 40.0 grams of ice would take ___ .

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Why do chromosomes condemce before cell division

Vlad [161]

Answer:This condensation is needed to allow the chromosomes to move along the mitotic spindle without becoming tangled or broken during their distribution to daughter cells. DNA in this highly condensed state can no longer be transcribed, so all RNA synthesis stops during mitosis.

Explanation: This condensation is needed to allow the chromosomes to move along the mitotic spindle without becoming tangled or broken during their distribution to daughter cells. DNA in this highly condensed state can no longer be transcribed, so all RNA synthesis stops during mitosis.

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3 years ago

The difference between a independent variable and a dependent variable

dexar [7]

Dependent is a variable who's outcome depends on another variable. independent is a variable who's outcome doesn't depend on another variable only the researchers experimenting.
hope this helps !

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4 years ago

Why is it important to use standard measurements and units in science

saul85 [17]

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3 years ago

Liquid can be converted into a gas select one:

podryga [215]

B. at it's boiling point

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4 years ago

Watching the assignment without knowing how to solve the questions is the worst thing to experience hope someone can help with t

frez [133]

Answer:

- 622.5kJ

Explanation:

1) 2NH3 + 3N2O ----> 4N2 + 3H2O ΔH° 1= - 1010kJ

- 3 (N2O + 3H2 ---> N2H4 + H2O ΔH° 2 = - 317 kJ)

2) 2NH3 + 3N2O ----> 4N2 + 3H2O ΔH° 1= - 1010kJ

- 3N2O - 9 H2 ----> - 3N2H4 - 3H2O - 3ΔH° 2 = 3*317 kJ

2NH3 + 3N2H4 --->4N2+9H2, ΔH° 1 - 3*ΔH° 2

2NH3 + 3N2H4 --->4N2+9H2, ΔH° 1 - 3*ΔH° 2

3) -(2NH3 +1/2O2 ---> N2H4 + H2O, ΔH°3 = -143 kJ)

-2NH3 - 1/2O2 ---> - N2H4 - H2O, - ΔH°3 = 143 kJ

2NH3 + 3N2H4 --->4N2+9H2, ΔH° 1 - 3*ΔH° 2

-2NH3 - 1/2O2 ---> - N2H4 - H2O, - ΔH°3 = 143 kJ

4N2H4 + H2O ---> 4N2 + 9H2 + 1/2O2, ΔH° 1 - 3*ΔH° 2 - ΔH°3

H2 + 1/2O2 ---> H2O, ΔH° 4 = - 286 kJ

9*(H2 + 1/2O2 ---> H2O, ΔH° 4 = - 286 kJ)

9H2+ 9/2 O2 ---> 9H2O, 9*ΔH° 4 = 9*(- 286) kJ

4N2H4 + H2O ---> 4N2 + 9H2 + 1/2O2, ΔH° 1 - 3*ΔH° 2 - ΔH°3

9H2+ 9/2 O2 ---> 9H2O, 9*ΔH° 4 = 9*(- 286) kJ

4N2H4 +4O2 --->4N2+8H2O, ΔH° 1 - 3*ΔH° 2 - ΔH°3 + 9*ΔH° 4

1/4*(4N2H4 +4O2 --->4N2+8H2O, ΔH° 1 - 3*ΔH° 2 - ΔH°3 + 9*ΔH° 4

N2H4 +O2 --->N2+2H2O, 1/4( ΔH° 1 - 3*ΔH° 2 - ΔH°3 + 9*ΔH° 4)

N2H4 +O2 --->N2+2,

1/4( ΔH° 1 - 3*ΔH° 2 - ΔH°3 + 9*ΔH° 4)=

=1/4(-1010kJ - 3*(-317kJ) - (-143kJ) + 9*(-286kJ))= - 622.5 kJ

7 0

3 years ago