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3 years ago

after 10 weeks, neither group reported a case of the flu. which procedure would have made the outcome of this study more valid?

1 answer:

5 0

I think you forgot to give the options along with the question. I am answering the question based on my knowledge and research. "Test a third group that does not receive the supplement" would be the procedure that would have made the <span>outcome of this study more valid. I hope the answer helps you.</span>

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When the equation Sn + HNO₃ → SnO₂ + NO₂ + H₂O is balanced in acidic solution, what is the smallest whole-number coefficient for

balu736 [363]

Answer:

Explanation:

Hello,

In this case, for the given reaction we first assign the oxidation state for each species:

$Sn^0 + H^+N^{5+}O^{-2}_3 \rightarrow Sn^{4+}O_2 + N^{4+}O^{2-}_2 + H^+_2O^-$

Whereas the half reactions are:

$Sn^0+2H_2O \rightarrow Sn^{4+}O_2 +4H^++4e^-\\\\H^++H^+N^{5+}O^{-2}_3 +1e^-\rightarrow N^{4+}O^{2-}_2+H_2O$

Next, we exchange the transferred electrons:

$1\times(Sn^0+2H_2O \rightarrow Sn^{4+}O_2 +4H^++4e^-)\\\\4\times (H^++H^+N^{5+}O^{-2}_3 +1e^-\rightarrow N^{4+}O^{2-}_2+H_2O)\\\\\\Sn^0+2H_2O \rightarrow Sn^{4+}O_2 +4H^++4e^-\\\\4H^++4H^+N^{5+}O^{-2}_3 +4e^-\rightarrow 4N^{4+}O^{2-}_2+4H_2O$

Afterwards, we add them to obtain:

$Sn^0+2H_2O+4H^++4H^+N^{5+}O^{-2}_3 \rightarrow Sn^{4+}O_2 +4H^++4N^{4+}O^{2-}_2+4H_2O$

By adding and subtracting common terms we obtain:

$Sn^0+4H^+N^{5+}O^{-2}_3 \rightarrow Sn^{4+}O_2 +4N^{4+}O^{2-}_2+2H_2O$

Finally, by removing the oxidation states we have:

$Sn + 4HNO_3 \rightarrow SnO_2 + 4NO_2 + 2H_2O$

Therefore, the smallest whole-number coefficient for Sn is 1.

Regards.

6 0

4 years ago

How does salt help melt the road?

QveST [7]

Lower the melting point

Explanation:

Salts helps to melt road by lowering the melting point. It acts as an impurity and generally, impurities low the melting point of substances.

Salts are used as an antifreeze.

Water freezes at 0°C and forms ice/snow which can impede human and vehicular movement.
When salt is added, it causes the depression of the freezing point by lowering it further.
The freezing point is pegged back at -6°C.
This way it takes more low temperature to freeze the water.
The salt acts as an impurity and causes the depression of melting point and widening of the melting range.

learn more:

Matter brainly.com/question/10972073

#learnwithBrainly

8 0

4 years ago

Read 2 more answers

The reducing agent in a material is the one that A. gains electrons. B. increases its atomic number. C. is reduced. D. is oxidiz

Bas_tet [7]

D. Is Oxidized Hope I helped.

4 0

4 years ago

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Fill in the coefficients that will balance the following reaction a0h2so4 + a1koh → a2k2so4 + a3hoh

Anuta_ua [19.1K]

A0 = 1
a1 = 2
a2 = 1
a3 = 2

This can be solved by guessing and checking and making sure that all atoms on the left side are accounted for on the right side. Both sides must have the same amount of atoms or the balancing is not correct.

7 0

3 years ago

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The vapor pressure of chloroform is 173.11 mm Hg at 25 °C. A nonvolatile, nonelectrolyte that dissolves in chloroform is aspirin

Over [174]

Answer:

VP (solution) = 171.56 mmHg

Explanation:

Vapor pressure of pure solvent(P°) - Vapor pressure of solution (P') = P° . Xm

Let's replace the data:

173.11 mmHg - P' = 173.11 mmHg . Xm

Let's determine the Xm (mole fraction for solute)

Mole fraction for solute = Moles of solute / Total moles

Total moles = Moles of solute + moles of solvent.

Let's determine the moles

Moles of solvent → 623.4 g / 119.4 g/mol = 5.22 moles

Moles of solute → 9.322 g / 180.1 g/mol = 0.052 moles

Total moles = 0.052 + 5.22 = 5.272 moles

Xm = 0.052 moles / 5.272 moles = 0.009 → 9/1000

173.11 mmHg - P' = 173.11 mmHg . 9/1000

P' = - (173.11 mmHg . 9/1000 - 173.11 mmHg)

P' = 171.56 mmHg

4 0

3 years ago

Read 2 more answers