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stealth61 [152]
3 years ago
11

Any science fair questions for 8th graders? please list at least 4

Chemistry
1 answer:
TEA [102]3 years ago
6 0

How does water purity affect surface tension?

When is the best time to plant soy beans?

Which material is the best insulator?

How does arch curvature affect load carrying strength?

How do different foundations stand up to earthquakes?

What sugars do yeast use?

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At liftoff, a space shuttle uses a solid mixture of ammonium  perchlorate and aluminum powder to obtain great thrust from the vo
klemol [59]

1 - A balanced equation for the reaction is 3NH4ClO4 + 3Al -------> Al2O3 + AlCl3 + 6H2O + 3NO

2 - Ammonium perchlorate is the oxidizing agent while aluminum powder is the reducing agent.

Molar mass of aluminum oxide = 102 g/mol;

The molar mass of ammonium perchlorate =117.5 g/mol.

From the equation of reaction 3 moles of ammonium perchlorate react with 3 moles of aluminum to produce 1 mole of aluminum oxide.

That is 3 x 7.5 g of ammonium perchlorate reacts with g of aluminum to produce 102 g/mol of aluminum oxide. Also 150g.

150 g of ammonium perchlorate produces (150 * 102)/(3*117.5) g of aluminum oxide = 43.4 g of aluminum oxide.

If you need to learn more about the balanced equation, click here;

brainly.com/question/26694427

#SPJ4

5 0
2 years ago
what is the volume percent of a solution prepared by adding enough water to 200.mL of acetone to make a total volume of 1.60L?
Elodia [21]
The  volume%  of  acetone  =  Ml  of    acetone/Ml  of  solution  x100
ml   of  acetone =200ml
ml  of  solution  = 1.60  x1000=1600ml

volume%  of acetone  is  therefore=  200/1600 x100= 12.5%
4 0
4 years ago
How many moles are there in 45.0 grams of sulfuric acid,<br> H2SO4?<br> moles
nydimaria [60]

Answer:

0.459 mol

Explanation:

M(H2SO4) = 2*1 + 32 +4*16 = 98 g/mol

45.0 g * 1 mol/98 g = 0.459 mol

7 0
3 years ago
If 6.5 mol NO2 react with 1.0 mol H20, how many moles of the excess reactant
harkovskaia [24]

Answer:

3.5 moles of NO2.

Explanation:

The balanced equation for the reaction is given below:

3NO2 + H2O —> NO + 2HNO3

Next, we shall determine the excess reactant. This is illustrated below:

From the balanced equation above,

3 moles of NO2 reacted with 1 moles H2O.

Therefore, 6.5 moles of NO2 will react with = (6.5 x 1)/3 = 2.17 moles of H2O.

From the above calculations, we can see that it will take a higher amount i.e 2.17 moles than what was given i.e 1 mole of H2O to react completely with 6.5 moles of NO2.

Therefore, NO2 is the excess reactant and H2O is the limiting reactant.

Next, we shall determine the number of mole of the excess reactant that reacted in the reaction. This is illustrated below:

From the balanced equation above, we can see that 3 moles of NO2 reacted with 1 mole of H2O.

Finally, we shall determine the leftover mole of the excess reactant after the reaction. This is illustrated below:

Given mole of NO2 = 6.5 moles

Reacted mole of NO2 = 3 moles

Leftover mole of NO2 =...?

Leftover mole = Given mole – Reacted mole

Leftover mole of NO2 = 6.5 – 3

Leftover mole of NO2 = 3.5 moles.

Therefore, 3.5 moles of NO2 remained after the reaction.

3 0
4 years ago
In its life history in which stage the silk moth spin the silk fibre for class 7th Plz answer ​
KiRa [710]

Answer:

in the 4\5thstage

Explanation:

because it's the time where silk worm separate

4 0
3 years ago
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