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kakasveta [241]
3 years ago
11

Science fair projects for 7th grade ideas?

Chemistry
2 answers:
allsm [11]3 years ago
8 0
Try the classic volcano project, grab construction paper and special liquid and some paint and etc and u good to go or u can try the twister idea of where u connect two soda cans and pour it out to make a twister tornado.
klio [65]3 years ago
4 0
Volcano         you make the volcano with baking soda and vinegera          
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alekssr [168]
Orange and maybe acorn
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Calculate the percent composition of Ca3P2
Afina-wow [57]
Calculate the molar mass of Ca3P2 in grams per mole or search for a chemical formula or substance.
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Which statement is true regarding a catalyst?
Alla [95]

Answer:

d). A catalyst lowers the activation energy for a chemical reaction.

Explanation:

From the given choices, it is true that a catalyst lowers the activation energy for a chemical reaction.

The activation energy is the energy barrier that must be overcome before a chemical reaction can occur.

Some reactions have very high activation energy and would not occur without the introduction of a catalyst.

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4 0
3 years ago
If 28.0 grams of Pb(NO3)2 react with 18.0 grams of NaI, what mass of PbI2 can be produced? Pb(NO3)2 + NaI → PbI2 + NaNO3
ss7ja [257]

Answer:- 27.7 grams of PbI_2 are produced.

Solution:- The balanced equation is:

Pb(NO_3)_2+2NaI\rightarrow PbI_2+2NaNO_3

let's convert the grams of each reactant to moles and calculate the grams of the product and see which one gives least amount of the product. This least amount would be the answer as the least amount we get is from the limiting reactant.

Molar mass of Pb(NO_3)_2 = 207.2+2(14.01)+6(16)  = 331.22 gram per molmolar mass of NaI = 22.99+126.90 = 149.89 gram per molMolar mass of [tex]PbI_2 = 207.2+2(126.90) = 461 gram per mol

let's do the calculations for the grams of the product for the given grams of each of the reactant:

28.0gPb(NO_3)_2(\frac{1molPb(NO_3)_2}{331.22gPb(NO_3)_2})(\frac{1molPbI_2}{1molPb(NO_3)_2})(\frac{461gPbI_2}{1molPbI_2})

= 39.0gPbI_2

18.0gNaI(\frac{1molNaI}{149.89gNaI})(\frac{1molPbI_2}{2molNaI})(\frac{461gPbI_2}{1molPbI_2})

= 27.7gPbI_2

From above calculations, NaI gives least amount of PbI_2, so the answer is, 27.7 g of PbI_2 are produced.

8 0
3 years ago
A piston starts out with a volume of 3.000 L at 250.0 K and 800.0 torr. It is heated to 500.0 K and has a new volume of 4.000 L.
valentinak56 [21]

Explаnаtion is in а file

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