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3 years ago

How is the mass of 1 mole of an element determined

1 answer:

3 0

One mole (abbreviated mol) is equal to 6.022×1023 molecular entities (Avogadro's number), and each element has a different molar mass depending on the weight of 6.022×1023 of its atoms (1 mole). The molar mass of any element can be determined by finding the atomic mass of the element on the periodic table.

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To aid in the prevention of tooth decay, it is recommended that drinking water contains 0.900 ppm fluoride (F-). A) How many g o

Romashka-Z-Leto [24]

Answer:

a) <u>1.740 g</u> of F- must be added to a cylindrical water reservoir

b) Grams of sodium fluoride, NaF, that contain this much fluoride:

3.84 g

Explanation:

Step 1. calculate the volume of the tank:

Volume of cylinder =

$\pi r^{2}h$ ,

Here r = radius of the cylinder = d/2

h = depth = 21.80m

$r=\frac{d}{2}$

$=\frac{3.36x10^{2}}{2}$

= 168 m

Volume =

$=\frac{22\times 168^{2}\times 21.80}{7}$

$=1.93\times 10^{6} m^{3}$

2.Convert ppm to g/m3 and Solve for mass of F-

$1ppm = 1g/m^{3}$

$0.9ppm = 0.9g/m^{3}$

Because both ppm and g/m3 are same quantity .

$g/m^{3} =\frac{mass\ of\ F-(g)}{Volume\ m^{3}}\times 10^{6}$

$0.9 =\frac{mass\ of\ F-}{1.93\times 10^{6} m^{3}}\times 10^{6}$

$mass\ of\ F- =1.740g$

mass of F- required = 1.740 g

3. Apply <u>mole concept </u>to calculate grams of sodium fluoride produced

mass of 1 mole of F2 = 38 g

mass of 1 mole of NaF = 42 g

(from periodic table calculate molar mass)

$2Na+F_{2}\rightarrow 2NaF$

Here 1 mole of F2 produce = 2 mole of NaF

So,

38 g of F2 produce = 2 x 42 g of NaF

38 g of F2 produce = 84 g of NaF

1 g of F2 produce = 84/38 g of NaF

1.74 g F2 produce =

$\frac {84}{38}\times 1.74$

1.74 g F2 produce = 3.84 g of NaF

3.84 g of NaF is produced

3 0

3 years ago

Help for extra points & brainlest !

SVETLANKA909090 [29]

Answer: i think is true

Explanation:

5 0

3 years ago

Read 2 more answers

Which of the following is an indication of a chemical reaction?

vovikov84 [41]

Answer:

All of the above

Explanation:

Their all chemical change

7 0

3 years ago

Place the steps of the action potential in order.

Ierofanga [76]

Answer:

-Reversal of the resting potential due to influx of sodium ions

-Mechanism that restores the resting membrane voltage and intracellular ionic concentrations

-Period during which potassium ions are diffusing out of the neuron because of a change in membrane permeability

-A brief reversal of membrane potential that travels along the axon

Explanation:

An action potential is a situation where the membrane potential is briefly reversed from -70mV to +30 mV

There are three steps of the moving action potential, including;

1) The depolarization step, where the membrane resting potential is reversed by the rush of sodium ions into a neuron

2) The repolarization, due to the closing of the voltage-gated sodium channels and the opening of the potassium channels, which is a mechanism that restores the membrane's resting voltage and the ionic concentration in the cell

3) Hyperpolarization, where due to some open potassium channels, there is an increased potassium permeability, and excessive efflux of potassium ions take place, which results in a dip in the membrane potential

4) The above three phases describe the phase of the action potential which is the brief reversal of membrane potential that travels along the axon

7 0

3 years ago

A balloon contains a fixed amount of helium. If the initial conditions are 1.12 liters, 3.00 atmospheres, and 19 degrees Celsius

Semmy [17]

Answer:

The final volume will be 3.39 liters

Explanation:

P1V1/T1 = P2V2/T2

P1 = 3 atm

T1 = 19( degrees celsius) + 273 = 292 K

V2 = TO BE DETERMINED

P2 =1 atm

T2 = 22( degrees celsius) + 273 = 295 k

P1V1/T1 = P2V2/T2

V2 = P1V1T2/P2T1 = (3)(1.12)(295)/(1)292) = 3.39 Liters

4 0

3 years ago