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3 years ago

An atom contains 31 protons,39neutrons and 31 electrons.Identify the mass number of this atom

Chemistry

1 answer:

AlladinOne [14]3 years ago

5 0

Answer:

Atomic mass =70

Explanation:

Mass number is total protons +total neutrons

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Which element on the periodic table has chemical properties that are most similar to those of carbon?

prisoha [69]

Silicon, it's bring brother would be the prime candidate, although its compounds are notably different from those of carbon.

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3 years ago

What is the freezing point of a solution of 498mL of water (solute) dissolved in 2.50 L of ethanol (solvent), C2H5OH? The densit

jok3333 [9.3K]

Answer:

Freezing T° of solution is -142.4°C

Explanation:

This excersise is about colligative properties, in this case freezing point depression,

ΔT = Kf . m . i

Where ΔT = Freezing T° of solvent - Freezing T° of solution

Kf = Cryoscopic constant

m = mol/kg (molality)

i = Number of ions dissolved.

Water is not ionic, so i = 1

Let's find out m.

We determine mass of water, by density

498ml . 1 g/mL = 498 g

We convert the mass of water to moles → 498 g . 1mol/18g = 27.6 moles

We determine mass of solvent by density

2500 mL . 0.789 g/mL = 1972.5 g

Notice, we had to convert L to mL to cancel units.

1 cm³ = 1 mL

We convert the mass from g to kg → 1972.5 g . 1kg /1000g = 1.97kg

We determine m = mol/kg → 27.6mol / 1.97kg = 13.9 m

Kf for ethanol is: 1.99 °C/m

Freezing T° for ethanol is: -114.6°C

We replace at formula: - 114.6°C - Freezing T° solution = 1.99 °C/m . 13.9 m . 1

- 114.6°C - Freezing T° solution = 27.8 °C

- Freezing T° solution = 27.8°C + 114.6°C

Freezing T° Solution = - 142.4 °C

7 0

3 years ago

n acid with a pKa of 8.0 is present in a solution with a pH of 6.0. What is the ratio of the protonated to the deprotonated form

Nady [450]

Answer : The ratio of the protonated to the deprotonated form of the acid is, 100

Explanation : Given,

$pK_a=8.0$

pH = 6.0

To calculate the ratio of the protonated to the deprotonated form of the acid we are using Henderson Hesselbach equation :

$pH=pK_a+\log \frac{[Salt]}{[Acid]}$

$pH=pK_a+\log \frac{[Deprotonated]}{[Protonated]}$

Now put all the given values in this expression, we get:

$6.0=8.0+\log \frac{[Deprotonated]}{[Protonated]}$

$\frac{[Deprotonated]}{[Protonated]}=0.01$

As per question, the ratio of the protonated to the deprotonated form of the acid will be:

$\frac{[Protonated]}{[Deprotonated]}=100$

Therefore, the ratio of the protonated to the deprotonated form of the acid is, 100

5 0

3 years ago

At 40 mph, how long does it take to travel 64 miles

gogolik [260]

1.5 hours
explanation: don’t have one just trust me

6 0

3 years ago

Convert the density of water, 1.00 g/mL to lb/ft3. Provide only the numerical value in your answer with the correct number of si

PtichkaEL [24]

Answer:

The density of water $1.00 g/ml=62.43 lbs/ft^3$ .

Explanation:

Density of water = 1.00 g/mL

1 lb = 453.592 g

$1 g=\frac{1}{453.592} lbs$

$ft^3=28316.8 mL$

$1 mL=\frac{1}{28316.8} ft^3$

Density of the water in $lb/ft^3$ :

$\frac{1.00 g}{1 mL}=\frac{1.00}{453.592 } lb\times \frac{28316.8 }{1 ft^3}$

$=62.43 lbs/ft^3$

The density of water $1.00 g/ml=62.43 lbs/ft^3$ .

3 0

4 years ago

An atom contains 31 protons,39neutrons and 31 electrons.Identify the mass number of this atom​

An atom contains 31 protons,39neutrons and 31 electrons.Identify the mass number of this atom