At STP, a 50.-gram sample of H2O() and a100.-gram sample of H2O() have

Students rolled a glass marble and a baseball down an inclined plane, as shown below, and made observations.

Alja [10]

The answer is b i just took the quiz and got it right|| k12.gca student

3 0

3 years ago

If you purchased 2.31 μCi of sulfur-35, how many disintegrations per second does the sample undergo when it is brand new?

nikklg [1K]

Answer:

8.547 x 10⁴disintegrations per second

Explanation:

To calculate the disintegrations per second as -

Given ,

2.31 μCi of sulfur -35 .

Since ,

1 Ci = 3.7 * 10 ¹⁰ Bq

1 μCi = 10 ⁻⁶ Ci

Hence ,

conversation is done as follows -

2.31 ( 1 * 10⁻⁶) * ( 3.7 * 10¹⁰)

= 8.547 x 10⁴

Hence ,

8.547 x 10⁴disintegrations per second , the sample undergo for it to be brand new .

3 0

3 years ago

Consider the process used to produce iron metal from its ore.

Dmitry_Shevchenko [17]

Answer:

223.4 grams of iron can be produced from 2.5 moles of Fe2O3 and 6.0 moles of CO.

Explanation:

The balanced reaction is:

Fe₂O₃ (s) + 3 CO(g) → 2 Fe(s) + 3 CO₂ (g)

By reaction stoichiometry (that is, the relationship between the amount of reagents and products in a chemical reaction), the following amounts of reactant and product participate in the reaction:

Fe₂O₃: 1 mole
CO: 3 moles
Fe: 2 moles
CO₂: 3 moles

Being:

Fe: 55.85 g/mole
O: 16 g/mole
C: 12 g/mole

the molar mass of the compounds participating in the reaction is:

Fe₂O₃: 2*55.85 g/mole + 3*16 g/mole= 159.7 g/mole
CO: 12 g/mole + 16 g/mole= 28 g/mole
Fe: 55.85 g/mole
CO₂: 12 g/mole + 2*16 g/mole= 44 g/mole

Then, by stoichiometry of the reaction, the following quantities participate in the reaction:

Fe₂O₃: 1 mole* 159.7 g/mole= 159.7 g
CO: 3 moles* 28 g/mole= 84 g
Fe: 2 moles* 55.85 g/mole= 111.7 g
CO₂: 3 moles* 44 g/mole= 132 g

The limiting reagent is one that is consumed first in its entirety, determining the amount of product in the reaction. When the limiting reagent is finished, the chemical reaction will stop.

So, first of all, you can apply the following rule of three: if by reaction stoichiometry 1 mole of Fe₂O₃ reacts with 3 moles of CO, then 2.5 moles of Fe₂O₃ react with how many moles of CO?

$moles of CO=\frac{2.5 moles of Fe_{2} O_{3}*3 moles of CO }{1 mole of Fe_{2} O_{3}}$

moles of CO= 7.5

But 7.5 moles of CO are not available, 6.0 moles are available. Since you have less moles than you need to react with 2.5 moles of Fe₂O₃, CO will be the limiting reagent.

Now you can apply the following rule of three: if by reaction stoichiometry 3 moles of CO produce with 111.7 grams of Fe, then 6 moles of CO will produce how much mass of Fe?

$mass of Fe=\frac{6 moles of CO*111.7 grams of Fe}{3 moles of CO}$