All categories

3 years ago

What should I do for science fair

Chemistry

2 answers:

Natasha2012 [34]3 years ago

8 0

Don't do a volcano at the same time you want to be creative and I personally feel that a volcano is too cliché.

Strike441 [17]3 years ago

5 0

You could Build a <span>Gumdrop Geodesic Dome !
</span>
Geodesic domes are approximately sphere-like structures made up of interconnected triangles. A famous geodesic dome is Spaceship Earth at EPCOT in Walt Disney World, Florida, but geodesic domes are also commonly found as climbing domes at playgrounds. In this science activity, you will get to build a simple geodesic dome using gumdrops and toothpicks. Once it is built, you may be surprised by how strong it is! Get ready to do some tasty engineering!

Materials:
<span> Gumdrops (11). Alternatively, jelly beans or other semi-firm, chewy candies may be used. <span> Toothpicks (25)
--
Instructions:
</span></span>
1.Attach five toothpicks together using the gumdrops to form a flat pentagon (five-pointed) shape. You should have a gumdrop at each point and a toothpick along each edge.
2.Poke two more toothpicks into each gumdrop, arranging the new toothpicks so that they are pointing up.
3.Take five new gumdrops and attach them to the top of the new toothpicks, putting two toothpicks into each gumdrop, to form triangles. (The pentagon should form the base of the triangle, and the new gumdrops should form the top point.) You should end up with five triangles this way.
4.Attach a toothpick between the top points of the triangles you just made, connecting the triangles together. This uses five toothpicks, and will create another pentagon shape, this time at the top of the dome.
5.Take five more toothpicks and poke one into each of the five gumdrops that make up the top pentagon. Arrange the new toothpicks so that they are pointing up. Then poke all five toothpicks into a gumdrop in the middle, and at the top, of the dome. Your geodesic dome is complete!
6.Gently press down on the top of your geodesic dome. If it does not break, try carefully pressing down on it a little more.

You might be interested in

The largest population that an environment can support is called _____.

Digiron [165]

Answer:

D) caring capacity

Explanation:

<h3>The largest population that an environment can support is called its carrying capacity.</h3>

<h2>hope it helps.</h2><h2>stay safe healthy and happy.</h2>

4 0

3 years ago

Read 2 more answers

Ideal gas (n 2.388 moles) is heated at constant volume from T1 299.5 K to final temperature T2 369.5 K. Calculate the work and h

bija089 [108]

Answer : The work, heat during the process and the change of entropy of the gas are, 0 J, 3333.003 J and -10 J respectively.

Explanation :

(a) At constant volume condition the entropy change of the gas is:

$\Delta S=-n\times C_v\ln \frac{T_2}{T_1}$

We know that,

The relation between the $C_p\text{ and }C_v$ for an ideal gas are :

$C_p-C_v=R$

As we are given :

$C_p=28.253J/K.mole$

$28.253J/K.mole-C_v=8.314J/K.mole$

$C_v=19.939J/K.mole$

Now we have to calculate the entropy change of the gas.

$\Delta S=-n\times C_v\ln \frac{T_2}{T_1}$

$\Delta S=-2.388\times 19.939J/K.mole\ln \frac{369.5K}{299.5K}=-10J$

(b) As we know that, the work done for isochoric (constant volume) is equal to zero. $(w=-pdV)$

(C) Heat during the process will be,

$q=n\times C_v\times (T_2-T_1)=2.388mole\times 19.939J/K.mole\times (369.5-299.5)K= 3333.003J$

Therefore, the work, heat during the process and the change of entropy of the gas are, 0 J, 3333.003 J and -10 J respectively.

7 0

3 years ago

Aspirin (C9H8O4) is synthesized by reacting salicylic acid (C7H6O3) with acetic anhydride (C4H6O3). The balanced equation isC7H6

prisoha [69]

<u>Answer:</u>

<u>For a:</u> The mass of acetic anhydride needed is 73.91 grams.

<u>For b:</u> The theoretical yield of aspirin is 130.43 grams.

<u>Explanation:</u>

To calculate the number of moles, we use the equation:

$\text{Number of moles}=\frac{\text{Given mass}}{\text{Molar mass}}$ .....(1)

<u>For a:</u>

Given mass of salicylic acid = $1.00\times 10^2g=100g$

Molar mass of salicylic acid = 138.121 g/mol

Putting values in equation 1, we get:

$\text{Moles of salicylic acid}=\frac{100g}{138.121g/mol}=0.724mol$

For the given chemical reaction:

$C_7H_6O_3+C_4H_6O_3\rightarrow C_9H_8O_4+CH_3COOH$

By stoichiometry of the reaction:

1 mole of salicylic acid reacts with 1 mole of acetic anhydride.

So, 0.724 moles of salicylic acid will react with = $\frac{1}{1}\times 0.724=0.724mol$ of acetic anhydride.

Now, to calculate the mass of acetic anhydride, we use equation 1:

Moles of acetic anhydride = 0.724 moles

Molar mass of acetic anhydride = 102.09 g/mol

Putting values in equation 1, we get:

$0.724mol=\frac{\text{Mass of acetic anhydride}}{102.09g/mol}\\\\\text{Mass of acetic anhydride}=73.91g$

Hence, the mass of acetic anhydride needed is 73.91 grams.

<u>For b:</u>

By stoichiometry of the reaction:

1 mole of salicylic acid is producing 1 mole of aspirin.

So, 0.724 moles of salicylic acid will produce = $\frac{1}{1}\times 0.724=0.724mol$ of aspirin.

Now, to calculate the mass of aspirin, we use equation 1:

Moles of aspirin = 0.724 moles

Molar mass of aspirin = 180.158 g/mol

Putting values in equation 1, we get:

$0.724mol=\frac{\text{Mass of aspirin}}{180.158g/mol}\\\\\text{Mass of aspirin}=130.43g$

Hence, the theoretical yield of aspirin is 130.43 grams.

4 0

4 years ago

How are strato volcanoes different from shield volcanoes?

Solnce55 [7]

Answer:

What is the difference between the two? Why do stratovolcanoes erupt violently and shield volcanoes do not? The difference is the viscosity of the lava. Low-viscosity lavas flow easily, erupt non-violently, and form gently-sloping shield volcanoes.

Explanation:

hope that helps !

4 0

3 years ago

Read 2 more answers

1. Mercury is most often obtained by roasting cinnabar (HgS). How many grams of cinnabar

Flauer [41]

Answer:

191.4 grams of cinnabar are required to obtain 165 grams of mercury.

Explanation:

The balanced reaction is:

HgS + O₂ ⇒ Hg + SO₂

By reaction stoichiometry, the following amounts of moles of each compound participate in the reaction:

HgS: 1 mole
O₂: 1 mole
Hg: 1 mole
SO₂: 1 mole

Being the molar mass of each compound:

HgS: 232g/mole
O₂: 32 g/mole
Hg: 200 g/mole
SO₂: 64 g/mole

the following mass amounts of each compound participate in the reaction:

HgS: 1 mole* 232 g/mole= 232 g
O₂: 1 mole* 32 g/mole= 32 g
Hg: 1 mole* 200 g/mole= 200 g
SO₂: 1 mole* 64 g/mole= 64 g

Then you can apply the following rule of three: if by stoichiometry 200 grams of Hg are formed from 232 grams of HgS , 165 grams of Hg are formed from how many grams of HgS?

$mass of HgS=\frac{165 grams of Hg*232 grams of HgS}{200 grams of Hg }$

mass of HgS= 191.4 grams

<em><u>191.4 grams of cinnabar are required to obtain 165 grams of mercury.</u></em>

5 0

3 years ago