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dalvyx [7]
3 years ago
13

When finding the mass number of an element do you round the atomic mass up or down? Ex. atomic mass of 74.9216, is the mass numb

er 75 or 74
Chemistry
2 answers:
Margaret [11]3 years ago
5 0
The total number of protons and neutrons in an atom is called the mass number. You can find the mass numberfor any element. The mass number canbe found by rounding the average atomic mass to the nearest whole number.
as an example
6.25 is closer to 6 than 7 so it is 6
6. 50 is closer to 7 so it is 7
you have to look at the thenth digit. if the number is 4 or less you have to round it down
if the tenth digit is 5 or greather than you have to round it up.
AleksAgata [21]3 years ago
3 0
Round the answer to the nearest whole number.
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How many grams of oxygen gas must react to give 2.10g of ZnO?
Advocard [28]
The chemical reaction is written as:

2Zn + O2 = 2ZnO

We are given the amount of the product to be produced from the reaction. We use this value and the relation of the substances in the reaction to calculate what is asked. We do as follows:

2.10 g ZnO ( 1 mol / 81.408 g ) ( 1  mol O2 / 2 mol ZnO ) ( 32 g / 1 mol ) = 0.414 g O2 is needed
8 0
3 years ago
What is the balanced equation for the reaction of aqueous cesium sulfate and aqueous barium perchlorate?
Aleksandr-060686 [28]

Answer:

The balanced chemical reaction is given as:

Cs_2SO_4(aq)+Ba(ClO_4)_2(aq)\rightarrow BaSO_4(s)+2CsClO_4(aq)

Explanation:

When aqueous cesium sulfate and aqueous barium perchlorate are mixed together it gives white precipitate barium sulfate and aqueous solution od cesium perchlorate.

The balanced chemical reaction is given as:

Cs_2SO_4(aq)+Ba(ClO_4)_2(aq)\rightarrow BaSO_4(s)+2CsClO_4(aq)

According to reaction, 1 mole of cesium sulfate reacts with 1 mole of barium perchlorate to give 1 mole of a white precipitate of barium sulfate and 2 moles of cesium perchlorate.

3 0
3 years ago
Purification of copper can be achieved by electrorefining copper from an impure copper anode onto a pure copper cathode in an el
givi [52]

Answer: The amount of time needed to plate 14.0 kg of copper onto the cathode is 295 hours

Explanation:

We are given:

Moles of electron = 1 mole

According to mole concept:

1 mole of an atom contains 6.022\times 10^{23} number of particles.

We know that:

Charge on 1 electron = 1.6\times 10^{-19}C

Charge on 1 mole of electrons = 1.6\times 10^{-19}\times 6.022\times 10^{23}=96500C

Cu^{2+}+2e^-\rightarrow Cu

2\times 96500=193000C is passed to deposit = 1 mole of copper

63.5 g of copper is deposited by = 193000 C

14\times 1000g=14000g of copper is deposited by =\frac{193000}{63.5}\times 14000=42551181 C

To calculate the time required, we use the equation:

I=\frac{q}{t}

where,

I = current passed = 40.0 A

q = total charge = 42551181 C

t = time required = ?

Putting values in above equation, we get:

40.0=\frac{42551181 C}{t}\\\\t=1063779sec

Converting this into hours, we use the conversion factor:

1 hr = 3600 seconds

So, 1063779s\times \frac{1hr}{3600s}=295hr

Hence, the amount of time needed to plate 14.0 kg of copper onto the cathode is 295 hours

3 0
3 years ago
Which of the following is an action-at-a-distance force? friction tension gravity air resistance
MissTica

Answer:

Action-at-a-Distance Forces. Frictional Force. Gravitational Force. Tension Force ... The force of gravity on earth is always equal to the weight of the object as ... The friction force is the force exerted by a surface as an object moves across it or ... The force of air resistance is often observed to oppose the motion of an object.

Explanation:

8 0
3 years ago
Read 2 more answers
Calculate the mass of hydrogen in 500 g of Al(C2H3O2)3
Zigmanuir [339]
<span>Answer is: the mass of hydrogen is 22,05 grams.
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n</span>(Al(C₂H₃O₂)₃) = m(Al(C₂H₃O₂)₃) ÷ M(Al(C₂H₃O₂)₃).
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n(Al(C₂H₃O₂)₃) = 2,45 mol.
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m(H) = 22,05 mol · 1 g/mol
m(H) = 22,05 g.

3 0
3 years ago
Read 2 more answers
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