Massive amounts of energy are contained in an atom's: Select one:

You need 270 ml of a 65% alcohol solution. on hand, you have a 90% alcohol mixture. how much of the 90% alcohol mixture and pure

olganol [36]

You must add 75 mL water to 195 mL 90 % alcohol to make 270 mL of 65 % alcohol.

Step 1. Calculate the volume of 90 % alcohol needed

You can use the dilution formula

V1×C1 = V2×C2

where

V1 and V2 are the volumes of the two solutions

C1 and C2 are the concentrations

You can solve the above formula to get

V2 = V1 × C1/C2

V1 = 270 mL; C1 = 65 %

V2 = ?; _____C2 = 90 %

∴V2 = 270 mL × (65 %/90 %) = 195 mL

You need 195 mL of 90 % alcohol to make 270 mL of 65 % RA

Step 2. Calculate the amount of water to add.

Volume of water = 270 mL – 195 mL = 75 mL

8 0

3 years ago

What is the volume of a balloon of gas at 842 mm Hg and -23° C, if its volume is 915 mL at a pressure of 1,170 mm Hg and a tempe

garik1379 [7]

Answer:
V₂ = 1070 mL or 1.07 L

Solution:

Data Given;
P₁ = 1170 mmHg

V₁ = 915 mL

T₁ = 24 °C + 273 K = 297 K

P₂ = 842 mmHg

V₂ = ?

T₂ = - 23 °C + 273 K = 250 K

According to Ideal gas equation,

P₁ V₁ / T₁ = P₂ V₂ / T₂

Solving for V₂,

V₂ = P₁ V₁ T₂ / P₂ T₁

Putting Values,

V₂ = (1170 mmHg × 915 mL × 250 K) ÷ (842 mmHg × 297 K)

V₂ = 1070 mL or 1.07 L

5 0

3 years ago

Describe the concept of using radioactive elements to establish an age for a fossil. Be sure to include how the parent and daugh

Nadusha1986 [10]

Answer:

The nuclear decay of radioactive elements is a process that is a useful tool for determining the absolute age of fossils and rocks. It is used as a clock, in which daughter elements or isotopes converted from parent isotopes by decaying at a particular time.

Radioactive decay rates are constant and do not change over time. It is measured in half-life. A half-life is a time it takes half of a parent isotope to decay and converted into a stable daughter isotope. How many parent isotopes and daughter isotopes present in the fossil or their abundance can help in determining the age of fossil or rock.

4 0

3 years ago

I have 2 samples of solid chalk (aka calcium carbonate). Sample A has a total mass of 4.12 g and Sample B has a total mass of 19

IRINA_888 [86]

Answer:

A) Sample B has more calcium carbonate molecules

Explanation:

M = Molar mass of calcium carbonate = 100.0869 g/mol

$N_A$ = Avogadro's number = $6.022\times 10^{23}\ \text{mol}^{-1}$

For the 4.12 g sample

Moles of a substance is given by

$n=\dfrac{m}{M}\\\Rightarrow n=\dfrac{4.12}{100.0869}\\\Rightarrow n=0.0411\ \text{mol}$

Number of molecules is given by

$nN_A=0.0411\times 6.022\times 10^{23}=2.48\times 10^{22}\ \text{molecules}$

For the 19.37 g sample

$n=\dfrac{19.37}{100.0869}\\\Rightarrow n=0.193\ \text{mol}$

Number of molecules is given by

$nN_A=0.193\times 6.022\times 10^{23}=1.16\times 10^{23}\ \text{molecules}$

$1.16\times 10^{23}\ \text{molecules}>2.48\times 10^{22}\ \text{molecules}$

So, sample B has more calcium carbonate molecules.

The ratio of the elements of carbon, oxygen, calcium atoms, ions, has to be same in both the samples otherwise the samples cannot be considered as calcium carbonate. Same is applicable for impurities. If there are impurites then the sample cannot be considered as calcium carbonate.

7 0

3 years ago

What do hydroelectric plants use to turn a turbine when producing electrical energy?

oksian1 [2.3K]

A. water
the word hydro means water

7 0

3 years ago