All categories

3 years ago

44 points! Will medal!

Chemistry

2 answers:

Dafna1 [17]3 years ago

7 0

A calorimeter contains 500 g of water at 25°C.....

the temperature of the water inside the calorimeter is 39.4°C.....

The specific heat of water is 4.18 J/g-°C.

energy needed to heat the water = specific heat * mass * temp difference

= 4.18 J/g-°C * 500 g * (39.4°C - 25°C)

= 4.18*500*14.4

= 30096J

or approx. 30kJ

viva [34]3 years ago

4 0

Energy=specific heat of water x mass of water x water's temperatures

=4.18x500x(39.4-25)

=30096J

You might be interested in

Which device uses on a non-renewable energy saurce?

aivan3 [116]

Nonrenewable energy resources include coal, natural gas, oil, and nuclear energy. Once these resources are used up, they cannot be replaced, which is a major problem for humanity as we are currently dependent on them to supply most of our energy needs

5 0

3 years ago

Which of these types of changes is a physical change?

Leto [7]

The correct answer is A. Can I get the Brainliest?

6 0

3 years ago

Read 2 more answers

What is the significance of the fact that chromosomes condense before they are moved.

natka813 [3]

Answer:

It allows for easier division of the sister chromatids into two identical chromosomes, one for each cell, and helps to prevent mistakes. You just studied 2 terms!

Explanation:

7 0

3 years ago

Indicate whether the following balanced equations involve oxidation-reduction. Check all that apply. Check all that apply. 2H2SO

guapka [62]

Answer : The balanced equations involve oxidation-reduction are:

(a) $2H_2SO_4(aq)+2NaBr(s)\rightarrow Br_2(l)+SO_2(g)+Na_2SO_4(aq)+2H_2O(l)$

(b) $3SO_2(g)+2HNO_3(aq)+2H_2O(l)\rightarrow 3H_2SO_4(aq)+2NO(g)$

(c) $NaI(aq)+3HOCl(aq)\rightarrow NaIO_3(aq)+3HCl(aq)$

Explanation :

Redox reaction or Oxidation-reduction reaction : It is defined as the reaction in which the oxidation and reduction reaction takes place simultaneously.

Oxidation reaction : It is defined as the reaction in which a substance looses its electrons. In this, oxidation state of an element increases. Or we can say that in oxidation, the loss of electrons takes place.

Reduction reaction : It is defined as the reaction in which a substance gains electrons. In this, oxidation state of an element decreases. Or we can say that in reduction, the gain of electrons takes place.

(a) The given chemical reaction is:

$2H_2SO_4(aq)+2NaBr(s)\rightarrow Br_2(l)+SO_2(g)+Na_2SO_4(aq)+2H_2O(l)$

This reaction involve oxidation-reduction reaction because the oxidation state bromine changes from (-1) to (0) which shows oxidation and sulfur changes from (+6) to (+4) which shows reduction.

(b) The given chemical reaction is:

$3SO_2(g)+2HNO_3(aq)+2H_2O(l)\rightarrow 3H_2SO_4(aq)+2NO(g)$

This reaction involve oxidation-reduction reaction because the oxidation state sulfur changes from (+4) to (+6) which shows oxidation and nitrogen changes from (+5) to (+2) which shows reduction.

(c) The given chemical reaction is:

$NaI(aq)+3HOCl(aq)\rightarrow NaIO_3(aq)+3HCl(aq)$

This reaction involve oxidation-reduction reaction because the oxidation state iodine changes from (-1) to (+5) which shows oxidation and chlorine changes from (+5) to (-1) which shows reduction.

(d) The given chemical reaction is:

$PBr_3(l)+3H_2O(l)\rightarrow H_3PO_3(aq)+3HBr(aq)$

This reaction does not involve oxidation-reduction reaction because the oxidation state of element present on reactant and product side are same.

3 0

3 years ago

Please help I have a test

natka813 [3]

Answer:

Pink- Lithium Salts or Lithium Nitrate (NO3), Yellow- Sodium Salts or Sodium Nitrate (NO3)

Explanation:

These chemicals (Sr, Ba, Cu, Ca, Na, Mg) are used because they create the colors for the firework. As you can see, the chemicals Nitrogen (N) and Oxygen (O) are combined with the color chemicals to make them combust.

The chart below explains the colorants used in firework creations:

<u>Color</u>= <u>Compound</u>

Red= strontium salts, lithium salts

lithium carbonate, Li2CO3 = red

strontium carbonate, SrCO3 = bright red

Orange= calcium salts

calcium chloride, CaCl2

calcium sulfate, CaSO4·xH2O, where x = 0,2,3,5

Gold= incandescence of iron (with carbon), charcoal, or lampblack

Yellow= sodium compounds

sodium nitrate, NaNO3

cryolite, Na3AlF6

Electric White= white-hot metal, such as magnesium or aluminum

barium oxide, BaO

Green= barium compounds + chlorine producer

barium chloride, BaCl+ = bright green

Blue= copper compounds + chlorine producer

copper acetoarsenite (Paris Green), Cu3As2O3Cu(C2H3O2)2 = blue

copper (I) chloride, CuCl = turquoise blue

Purple= mixture of strontium (red) and copper (blue) compounds

Silver= burning aluminum, titanium, or magnesium powder or flakes

I hope this answers the question you have! If not, I apologize.

8 0

3 years ago