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Elis [28]
3 years ago
10

3. A scientific investigation typically begins when a scientist makes observations that lead to the formation of a (n) _________

_________________?
A.law
B.theory
C.hypothesis
D.none of the above
Chemistry
1 answer:
Artist 52 [7]3 years ago
8 0

Answer:

C. Hypothesis

Explanation:

A hypothesis is usually the start of a scientific investigation.

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If 5 mol of oxygen gas effuses through an opening in 10 seconds, how long will it take for the same amount of hydrogen gas to ef
andrezito [222]

Answer:

B

Explanation:

Recall the law of effusion:

\displaystyle \frac{r_1}{r_2} = \sqrt{ \frac{\mathcal{M}_2}{\mathcal{M}_1} }

Because 5 mol of oxygen was effused in 10 seconds, the rate is 0.5 mol/s.

Let the rate of oxygen be <em>r</em>₁ and the rate of hydrogen be <em>r</em>₂.

The molecular weight of oxygen gas is 32.00 g/mol and the molecular weight of hydrogen gas is 2.02 g/mol.

Substitute and solve for <em>r</em>₂:

\displaystyle \begin{aligned} \frac{(0.5\text{ mol/s})}{r_2} & = \sqrt{\frac{(2.02\text{ g/mol})}{(32.00\text{ g/mol})}} \\ \\  r_2 & = \frac{0.5\text{ mol/s}}{\sqrt{\dfrac{(2.02\text{ g/mol})}{(32.00\text{ g/mol})}}} \\ \\ & = 2.0\text{ mol/s}\end{aligned}

Because there are 5 moles of hydrogen gas:

\displaystyle 5.0\text{ mol} \cdot \frac{1\text{ s}}{2.0\text{ mol}} = 2.5\text{ s}

In conclusion, it will take about 2.5 seconds for the hydrogen gas to effuse.

Check: Because hydrogen gas is lighter than oxygen gas, we expect that hydrogen gas will effuse quicker than oxygen gas.

6 0
2 years ago
A typical air sample in the lungs contains oxygen at 100 mmhg, nitrogen at 573 mmhg, carbon dioxide at 40 mmhg, and water vapor
nikdorinn [45]
  it  is  called the  partial pressure   because    it  is    pressure  that   is  exerted by  each gas in  a mixture of  gases if it occupy  the same   volume  of  it  own.  the  the partial pressure  of oxygen  in the air sample above is  100 mm hg, that of  carbon dioxide is 40 mmhg, for   water vapor  47 mmhg. and that of  nitrogen  is 573 mmhg
4 0
3 years ago
Observation And Assessment
Sloan [31]
I'm confused here??????
5 0
3 years ago
Nitric oxide reacts with chlorine to form nocl. the data refer to 298 k. 2no(g) + cl2(g) → 2nocl(g) substance: no(g) cl2(g) nocl
tigry1 [53]

Answer:

- 10.555 kJ/mol.

Explanation:

∵ ∆G°rxn = ∆H°rxn - T∆S°rxn.

Where, ∆G°rxn is the standard free energy change of the reaction (J/mol).

∆H°rxn is the standard enthalpy change of the reaction (J/mol).

T is the temperature of the reaction (K).

∆S°rxn is the standard entorpy change of the reaction (J/mol.K).

  • Calculating ∆H°rxn:

∵ ∆H°rxn = ∑∆H°products - ∑∆H°reactants

<em>∴ ∆H°rxn = (2 x ∆H°f NOCl) - (1 x ∆H°f Cl₂) - (2 x ∆H°f NO) </em>= (2 x 51.71 kJ/mol) - (1 x 0) - (2 x 90.29 kJ/mol) = - 77.16 kJ/mol.

  • Calculating ∆S°rxn:

∵  ∆S°rxn = ∑∆S°products - ∑∆S°reactants

<em>∴ ∆S°rxn = (2 x ∆S° NOCl) - (1 x ∆S° Cl₂) - (2 x ∆S° NO) </em>= (2 x 261.6 J/mol.K) - (1 x 223.0 J/mol.K) - (2 x 210.65 J/mol.K) =<em> - 121.1 J/mol.K. = - 0.1211 kJ/mol.K.</em>

<em></em>

  • Calculating ∆G°rxn:

∵ ∆G°rxn = ∆H°rxn - T∆S°rxn.

<em>∴ ∆G°rxn = ∆H°rxn - T∆S°rxn </em>= (- 77.16 kJ/mol) - (550 K)(- 0.1211 kJ/mol.K) = <em>- 10.555 kJ/mol.</em>

4 0
3 years ago
Identify each property below as more characteristic of a metal or a nonmetal.
Romashka [77]
A. Nonmetallic
B. Nonmetallic
C. Metallic
D. Nonmetallic
E. Metallic
5 0
3 years ago
Read 2 more answers
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