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2 years ago

The half-life of bismuth is 5 days. How much of a 100 gram sample will remain after 20 days?

1 answer:

8 0

Half-life is the duration needed for a compound to decay into half of its initial weight. In this case, the initial weight is 100gram. The calculation for the final weight should be:

final weight= initial weight * (1/2)^(duration/half-life)
final weight= 100 grams * (1/2)^(20days/5 days)
final weight= 100 grams * (1/2)^(4)
final weight= 100 * 1/16= 100/16 gram= 6.25 grams

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How many grams of NH3 can be produced from 12.0g of H2?

RSB [31]

Answer:

Balanced reaction:

3 H2 (g) + N2 (g) → 2 NH3 (g)

Use stoichiometry to convert g of H2 to g of NH3. The process would be:

g H2 → mol H2 → mol NH3 → g NH3

12.0 g H2 x (1 mol H2 / 2.02 g H2) x (2 mol NH3 / 3 mol H2) x (17.03 g NH3 / 1 mol NH3) = 67.4 g NH3

Explanation: See above

Hope this helps, friend.

8 0

1 year ago

A sample of a substance has a mass of 7.5 g and a volume of 2.5 cubic centimeters. What is the object’s density?

Inga [223]

Answer:

option A is the correct answer .

Explanation:

as density = mass per unit volume

density = 7.5/2.5 = 3 gm / cm³ ..is the answer ...

pls mark my answer as brainlist plzzzz and plz vote

7 0

2 years ago

Read 2 more answers

Suppose a 250. mL flask is filled with 0.30 mol of N_2 and 0.70 mol of NO. The following reaction becomes possible:N_2(g) +O2 →

Inessa [10]

Answer:

0.4 M

Explanation:

Equilibrium occurs when the velocity of the formation of the products is equal to the velocity of the formation of the reactants. It can be described by the equilibrium constant, which is the multiplication of the concentration of the products elevated by their coefficients divided by the multiplication of the concentration of the reactants elevated by their coefficients. So, let's do an equilibrium chart for the reaction.

Because there's no O₂ in the beginning, the NO will decompose:

N₂(g) + O₂(g) ⇄ 2NO(g)

0.30 0 0.70 Initial

+x +x -2x Reacts (the stoichiometry is 1:1:2)

0.30+x x 0.70-2x Equilibrium

The equilibrium concentrations are the number of moles divided by the volume (0.250 L):

[N₂] = (0.30 + x)/0.250

[O₂] = x/0.25

[NO] = (0.70 - 2x)/0.250

K = [NO]²/([N₂]*[O₂])

K = $\frac{(\frac{0.70 -2x}{0.250})^2 }{\frac{0.30+x}{0.250}*\frac{x}{0.250} }$

7.70 = (0.70-2x)²/[(0.30+x)*x]

7.70 = (0.49 - 2.80x + 4x²)/(0.30x + x²)

4x² - 2.80x + 0.49 = 2.31x + 7.70x²

3.7x² + 5.11x - 0.49 = 0

Solving in a graphical calculator (or by Bhaskara's equation), x>0 and x<0.70

x = 0.09 mol

Thus,

[O₂] = 0.09/0.250 = 0.36 M ≅ 0.4 M

3 0

2 years ago

PLEASE ANSWER CORRECTLY! MARKING BRANLIEST!

seropon [69]

Answer: oil spill, forest fire

Explanation:

The short term environmental change is a change that occur in an environment which exerts it's effect over the environment and the living beings for a short duration. The damage caused by the short term environmental change can be recovered in a short time. The oil spill and forests fire are the example of short term environmental changes.

The oil spill will reduce the abundance of the aquatic species until the oil is circulated out at the bay of the water body therefore, it is a short term environmental change.

Forests fire will remain ignited for a short period but can be destructive enough to cause damage to flora and fauna species. As time passes the reduced populations of flora and fauna can be recovered again.

5 0

2 years ago

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Percent yield is the quantity of product actually produced compared to the quantity _______.

ss7ja [257]

Answer:

Of expected product

Explanation:

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2 years ago