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3 years ago

Write the formulae for the following and calculate the molecular mass for each one of them,

Chemistry

1 answer:

tatuchka [14]3 years ago

8 0

Explanation:

a) NaHCO₃

= 23 + 1 + 12 + 16×3

= 23 + 1 + 12 + 48

= 84 g/mol

b) CaO

= 40 + 16

= 56 g/mol

c) NaCl

= 23 + 35.5

= 58.5 g/mol

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In the laboratory, hydrogen gas is usually made by the following reaction: Zn(s) + 2 HCl(aq) → H2(g) + ZnCl2(aq) How many liters

IrinaK [193]

Answer: The volume of hydrogen gas collected over water is 2.13 L

Explanation:

To calculate the number of moles, we use the equation:

$\text{Number of moles}=\frac{\text{Given mass}}{\text{Molar mass}}$

Given mass of zinc = 5.566 g

Molar mass of zinc = 65.4 g/mol

Putting values in above equation, we get:

$\text{Moles of zinc}=\frac{5.566g}{65.4g/mol}=0.0851mol$

For the given chemical reaction:

$Zn(s)+2HCl(aq.)\rightarrow H_2(g)+ZnCl_2(aq.)$

As, HCl is present in excess. So, it is considered as an excess reagent.

Zinc is considered as a limiting reagent because it limits the formation of product.

By Stoichiometry of the reaction:

1 mole of zinc produces 1 mole of hydrogen gas.

So, 0.0851 moles of zinc will produce = $\frac{1}[1}\times 0.0851=0.0851mol$ of hydrogen gas

To calculate the volume of hydrogen gas, we use ideal gas equation, which is:

PV = nRT

where,

P = Pressure of hydrogen gas = Total atmospheric pressure - vapor pressure of water = (752 - 18.65) mmHg = 733.35 mmHg

V = Volume of the hydrogen gas

n = number of moles of gas = 0.0851 moles

R = Gas constant = $62.3637\text{ L.mmHg }mol^{-1}K^{-1}$

T = Temperature of hydrogen gas = $21^oC=[21+273]K=294K$

Putting values in above equation, we get:

$733.35mmHg\times V=0.0851mol\times 62.3637\text{ L.mmHg }mol^{-1}K^{-1}\times 294K\\\\V=\frac{0.0851\times 62.3637\times 294}{733.35}=2.13L$

Hence, the volume of hydrogen gas collected over water is 2.13 L

5 0

3 years ago

What are the three conditions that can cause a chemicl reactions, give examples? Help me plz

finlep [7]

Acid. that’s all i know.

7 0

2 years ago

In the diagram, above, marker E is pointing to a __________, which is the “winding” shape that a river can take and its shape is

Liula [17]

Answer:

meander

Explanation:

A meander is the the “winding” shape that a river can take. It is is one of a series of regular sinuous curves, bends, loops, turns, or windings in the channel of a river, stream, or other watercourse(wikipedia).

A meander is formed when water in the river erodes the banks just outside its channel. The water then deposits some sediments inside the channel.

5 0

2 years ago

Which of the following represents radiant energy being converted to chemical energy?

Arte-miy333 [17]

ANSWER

The correct answer is A

EXPLANATION

Plants manufacture their on food by the process of photosynthesis. During this process, plants trap radiant energy from the sun by the help of chlorophyll in the leaves.

Radiant energy with other raw materials such as water, carbon dioxide and mineral salts is converted to food (in the form of starch) which contains chemical energy.

6 0

3 years ago

Find the linear function Cequalsf(F) that gives the reading on the Celsius temperature scale corresponding to a reading on the

padilas [110]

Answer:

C = (5/9) F - (160/9)

They both read equal at Z = - 40

Explanation:

We are looking for a linear function so we can write the following condition

Y = aX + b

Applying it to the exercise we got C = a F + b

Let's use the facts that C = 0 when F = 32 and C = 100 when F = 212

0 = 32 a + b (1)

100 = 212 a + b (2)

From (1) b = - 32 a , when we replace this in (2) we obtain a = (5/9)

and b = - (5/9)32 = - 160/9

Finally the linear function is C = (5/9) F - (160/9)

Both readings are equal at a Z number so

Z = (5/9) Z - 160/9

(4/9) Z = -160/9 and Z = - 40

6 0

3 years ago