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1 year ago

According to Frank, what is the “10 second rule"?

Chemistry

1 answer:

Lelechka [254]1 year ago

4 0

Answer:

The first option, aka Opick it up off the gound within 10 seconds, and it's o.k. to eat

Explanation:

The 10 second rule is a rule when you drop foods, but if you get it off the floor under 10 seconds, you can eat it.

Did you know that food picked up under 10 seconds and after 10 seconds has almost the same number of bacterias? The 10 second rule is basically worthless.

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In the equation:

Ksenya-84 [330]

Answer:

B) 16 g

Explanation:

2H₂ + O₂ → 2H₂O

First we convert 4 moles of O₂ into moles of H₂, using the stoichiometric coefficients of the balanced reaction:

4 mol O₂ * $\frac{2molH_2}{1molO_2}$ = 8 mol H₂

Finally we convert 8 moles of H₂ into grams, using its molar mass:

8 mol H₂ * 2 g/mol = 16 g

Thus, the correct answer is option B).

6 0

2 years ago

You need to make 10.0 L of 1.2 M KNO3. What molar ( concentration) would the potassium nitrate solution need to be if you were t

solniwko [45]

Answer:

2.5L [NaCl] concentrate needs to be 4.8 Molar solution before dilution to prep 10L of 1.2M KNO₃ solution.

Explanation:

Generally, moles of solute in solution before dilution must equal moles of solute after dilution.

By definition Molarity = moles solute/volume of solution in Liters

=> moles solute = Molarity x Volume (L)

Apply moles before dilution = moles after dilution ...

=> (Molarity X Volume)before dilution = (Molarity X Volume)after dilution

=> (M)(2.5L)before = (1.2M)(10.0L)after

=> Molarity of 2.5L concentrate = (1.2M)(10.0L)/(2.5L) = 4.8 Molar concentrate

6 0

2 years ago

Hydrogen sulfide burns form sulfur dioxide:

Helga [31]

Answer: 404.04 kJ.

Explanation:

To calculate the moles, we use the equation:

$\text{Number of moles}=\frac{\text{Given mass}}{\text {Molar mass}}$

moles of $H_2S$

$\text{Number of moles}=\frac{26.7g}{34.1g/mol}=0.78moles$

$2H_2S(g)+3O_2(g)\rightarrow 2SO_2(g)+2H_2O(g)$ $\Delta H=-1036kJ$

According to stoichiometry :

2 moles of $H_2S$ on burning produces = 1036 kJ

Thus 0.78 moles of $H_2S$ on burning produces = $\frac{1036kJ}{2}\times 0.78=404.04$

Thus the enthalpy change when burning 26.7 g of hydrogen sulfide is 404.04 kJ.

7 0

2 years ago

A sample of gas (1.9 mol) is in a flask at 21 °C and 697 mm Hg. The flask is opened and more gas is added to the flask. The new

Artyom0805 [142]

Answer: There are now 2.07 moles of gas in the flask.

Explanation:

$PV=nRT$

P= Pressure of the gas = 697 mmHg = 0.92 atm (760 mmHg= 1 atm)

V= Volume of gas = volume of container = ?

n = number of moles = 1.9

T = Temperature of the gas = 21°C=(21+273)K= 294 K (0°C = 273 K)

R= Value of gas constant = 0.0821 Latm\K mol

$V=\frac{nRT}{P}=\frac{1.9\times 0.0821 \times 294}{0.92}=49.8L$

When more gas is added to the flask. The new pressure is 775 mm Hg and the temperature is now 26 °C, but the volume remains same.Thus again using ideal gas equation to find number of moles.

$PV=nRT$

P= Pressure of the gas = 775 mmHg = 1.02 atm (760 mmHg= 1 atm)

V= Volume of gas = volume of container = 49.8 L

n = number of moles = ?

T = Temperature of the gas = 26°C=(26+273)K= 299 K (0°C = 273 K)

R= Value of gas constant = 0.0821 Latm\K mol

$n=\frac{PV}{RT}=\frac{1.02\times 49.8}{0.0821\times 299}=2.07moles$

Thus the now the container contains 2.07 moles.

6 0

2 years ago

Why are scientist surprised to find coal in artic

Vilka [71]

Coal=fire and in the artic its hard to build a fire

8 0

2 years ago

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