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3 years ago

Find the average speed of a person who swims 105 m in 70 s

Chemistry

1 answer:

spin [16.1K]3 years ago

4 0

Answer:

v = 1.5 m/s

Explanation:

Given that,

Distance covered by a person, d = 105 m

Time taken, t = 70 s

We need to find the average speed of the person. We know that the average speed is given by :

$v=\dfrac{d}{t}\\\\v=\dfrac{105\ m}{70\ s}\\\\v=1.5\ m/s$

So, the average speed of the person is equal to 1.5 m/s.

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A bottle of wine contains 12.8% ethanol by volume. The density of ethanol (CH3OH) is 0.789 g/cm. Calculate the concentratic etha

Scrat [10]

Answer : The mass percent of ethanol is, 10.38 % and the molality of ethanol is, 2.52 mole/kg

Explanation :

In wine, the solute and solvent are ethanol and water respectively.

Given :

12.8 % ethanol by volume means 12.8 mL ethanol present in 100 mL solution.

Volume of ethanol = 12.8 mL

Volume of solution = 100 mL

Volume of water = 100 - 12.8 = 87.2 mL

Density of ethanol = $0.789g/cm^3=0.789g/mL$

Density of water = 1 g/mL

Now we have to calculate the mass of ethanol and water.

$\text{Mass of ethanol}=\text{Density of ethanol}\times \text{Volume of ethanol}=0.789g/mL\times 12.8mL=10.1g$

and,

$\text{Mass of water}=\text{Density of water}\times \text{Volume of water}=1g/mL\times 87.2mL=87.2g$

Now we have to calculate the total mass of 100 mL of wine.

Total mass of 100 mL of wine = 10.1 + 87.2 = 97.3 g

Now we have to calculate the mass percent of ethanol.

$\text{Mass of percent of ethanol}=\frac{\text{Mass of ethanol}}{\text{Total mass of solution}}\times 100$

$\text{Mass of percent of ethanol}=\frac{10.1g}{97.3g}\times 100=10.38\%$

The mass percent of ethanol is, 10.38 %

Now we have to calculate the molality.

$Molality=\frac{\text{Mass of solute}\times 1000}{\text{Molar mass of solute}\times \text{Mass of solvent}}$

Molar mass of ethanol = 46 g/mole

$Molality=\frac{10.1g\times 1000}{46g/mole\times 87.2g}=2.52mole/kg$

The molality of ethanol is, 2.52 mole/kg

6 0

3 years ago

Chemistry help please! I just need to make sure the answers correct.... Thank you!

Veronika [31]

1. At constant tempaerature and pressure, 3 tablets produce 600cm^3 of gas
Thus calculating for 1 tablet that produces 600 / 3 = 200 cm^3
So now two tablets produce 200 x 2 = 400 cm^3
2. We have the equation PV = nRT, n being the number of moles
Pressure P = 1,000 kPa
Volume V = 3 L
R = 8.31 L kPa/mol-K
Temperature T = 298 K
n = PV / RT = (1000 x 3) / (8.31 x 298) = 3000 / 2476.38 = 1.21 moles
Number of moles = 1.21 moles.

8 0

3 years ago

Two molecules of one reactant combine with 3 molecules of another to produce 5 molecules of a product.

maksim [4K]

Answer:

A = 2A + 3B → 5C

Explanation:

The two molecule of A and three molecules of B will react to form the five molecules of C.

2A + 3B → 5C

Other options are incorrect because,

B = A₂ + B₃ → C₅

in this reaction one molecule of A₂ and one molecule of B₃ combine to form one molecule of C₅.

C = 2A + 5B → 3C

in this reaction two molecules of A and five molecules of B combine to form three molecule of C.

D = A₂ + B₃ → C₃

in this reaction one molecule of A₂ and one molecule of B₃ combine to from one molecule of C₃.

3 0

3 years ago

Why don't siblings look exactly alike

marusya05 [52]

Answer:

Your genes play a big role in making you who you are. ... But brothers and sisters don't look exactly alike because everyone (including parents) actually has two copies of most of their genes. And these copies can be different. Parents pass one of their two copies of each of their genes to their kids.

3 0

3 years ago

When weak acids react with strong bases, the H+ from the weak acid is transferred to the:

frosja888 [35]

It teacts with OH and makes water and salt

5 0

3 years ago