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-BARSIC- [3]
3 years ago
8

A sample of polonium-210 has an initial mass of 390 milligrams (mg). If the half-life of polonium-210 is 36 days, how many mg of

the sample remains after 72 days?
A.
392 mg

B.
195 mg

C.
97.5 mg

D.
48.75 mg
Chemistry
1 answer:
Over [174]3 years ago
3 0

Answer:

C

Explanation:

I got this question right on my test.

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Paul has different spoons for cooking. He told Sue that he likes to stir hot food with a wooden spoon because it does not burn h
IceJOKER [234]

Answer:

Sue was not right as wood is not a heat conductor and will not allow heat to pass through the spoon thus keeping the hand safe. In a meatal spoon, heat can pass through and burn the hand as meatal is a good conductor of heat.

8 0
3 years ago
Butane, C4H10, reacts with oxygen, O2, to form water, H2O, and carbon dioxide, CO2, as shown in the following chemical equation:
Wittaler [7]
The balanced chemical reaction is:

<span>2C4H10(g)+13O2(g)->10H2O(g)+8CO2(g) 
</span>
<span>Calculate the mass of water produced when 1.77 grams of butane reacts with excessive oxygen?
</span>1.77 g C4H10 (1 mol C4H10/58.14 g C4H10) (10 mol H2O / 2 mol C4H10) ( 1.01 g H2O / 1 mol H2O ) = <span>0.15 g H2O

</span><span>Calculate the mass of butane needed to produce 71.6 of carbon dioxide.
</span>71.6 g CO2 (1 mol CO2/ 44.01 g CO2) ( 2 mol C4H10 / 8 mol CO2 ) (58.14 g C4H10 / 1 mol C4H10 ) = 23.65 g C4H10
4 0
3 years ago
Read 2 more answers
Explain why the nucleus of an atom is positively charged but the overall charge of an atom is neutral
gtnhenbr [62]

Answer:

The nucleus is positively charged because it contains all of the protons however the charge of an atom is neutral because there is an equal amount of protons (positive) and electrons (negative) meaning the opposite charges cancel each other out therefore making the atoms overall charge neutral.

Explanation:

8 0
2 years ago
Ammonia, NH 3 , may react with oxygen to form nitrogen gas and water. 4 NH 3 ( aq ) + 3 O 2 ( g ) ⟶ 2 N 2 ( g ) + 6 H 2 O ( l )
Alex Ar [27]

Answer:

The limiting reactant is NH₃

0.0186moles of N₂ are the one produced by the limiting reactant

0.020 moles of N₂ are the one produced by the reactant in excess

Explanation:

This is the reaction

4NH₃ + 3O₂  → 2N₂ + 6H₂O

We should calculate the moles of each reactant

Mass / Molar mass = Moles

3.55 g / 17g/m = 0.208 moles NH₃

5.33 g / 32g/m = 0.166 moles O₂

4 moles of ammonia react with 3 moles of oxygen

0.208 moles of ammonia react with (0.208  .3)/4 = 0.156 moles O₂

We have 0.166 moles of O₂ and we need 0.156 moles, so O₂ is the reactant in excess.

3 moles of O₂ react with 4 moles of NH₃

0.166 moles of O₂ react with (0.166 . 4)/ 3 = 0.221 moles

We have 0.208 moles NH₃ and we need 0.221, so NH₃ is the limiting reactant.

To know the moles of N₂, let's apply the Ideal Gas Law

P.V =n.R.T

1atm . 0.450L = n . 0.082 . 295K

0.450 / (0.082 .295) = 0.0186 moles

If we have 100 % yield reaction:

4 moles NH₃ make 2 moles N₂

0.208 moles NH₃ make (0.208  .2)/4 = 0.104 moles

So the % yield reaction is.

0.104 moles ___ 100%

0.0186 moles ___ 17.9%

0.0186moles of N₂ are the one produced by the limiting reactant.

3 moles of O₂ produce 2 moles N₂

0.166 moles O₂ produce  (0.166  .2)/3 = 0.111 moles

Now, we apply the yield.

100% ____ 0.111 moles

17.9% = 0.020 moles

8 0
3 years ago
Read 2 more answers
Which of these compounds has the correct chemical formula? 1. ba3po4 2. (nh4)2so4 3. mg2oh 4. lif2 5. caoh?
sergiy2304 [10]
Ba3PO4 is not neutral, it is positive.  (NH4)2SO4 is neutral, the charges cancel.
Mg2OH is not neutral, it is positive.  LiF2 is not neutral, it is negative.  CaOH is not neutral, it is positive.  The answer is (NH4)2SO4, correct ions will have a neutral charge.
4 0
3 years ago
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