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3 years ago

EASY 8TH GRADE SCIENCE, PLEASE HELP!!!!!!!!

Chemistry

2 answers:

SCORPION-xisa [38]3 years ago

8 0

A. Protons in the atom

proof checked 100% correct answer

Natalka [10]3 years ago

5 0

D is the answer! I know it!

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Current passes through a solution of sodium chloride. In 1.00 second, 2.68×1016Na+ ions arrive at the negative electrode and 3.9

EleoNora [17]

Answer : The current passing between the electrodes is, $1.056\times 10^{-2}A$

Explanation :

First we have to calculate the charge of sodium ion.

$q=ne$

where,

q = charge of sodium ion

n = number of sodium ion = $2.68\times 10^{16}$

e = charge on electron = $1.6\times 10^{-19}C$

Now put all the given values in the above formula, we get:

$q=(2.68\times 10^{16})\times (1.6\times 10^{-19}C)=4.288\times 10^{-3}C$

Now we have to calculate the charge of chlorine ion.

$q'=ne$

where,

q' = charge of chlorine ion

n = number of chlorine ion = $3.92\times 10^{16}$

e = charge on electron = $1.6\times 10^{-19}C$

Now put all the given values in the above formula, we get:

$q'=(3.92\times 10^{16})\times (1.6\times 10^{-19}C)=6.272\times 10^{-3}C$

Now we have to calculate the current passing between the electrodes.

$I=\frac{q}{t}+\frac{q'}{t}$

$I=\frac{4.288\times 10^{-3}}{1.00}+\frac{6.272\times 10^{-3}}{1.00}$

$I=1.056\times 10^{-2}A$

Thus, the current passing between the electrodes is, $1.056\times 10^{-2}A$

4 0

3 years ago

what mass of copper is produce when Zinc is added to a solution containing 31.9g copper (ii) tetraoxosulphate (vi)

Sergio [31]

12.7 grams of copper will be produced.

<h3><u>Explanation</u>:</h3>

Copper is placed below zinc in the metal activity series. This means zinc can replace copper from its salt. Here zinc is added to the salt solution of copper sulphate. The reaction involved is

CuSO4 +Zn =ZnSO4 +Cu.

Zinc sulphate is soluble in the solution and rose red copper will be precipitated from the solution.

From the chemical equation we can see that 1 mole of zinc replaces 1 mole of copper. As no mass of zinc added is mentioned we will assume that excess of zinc is added.

Atomic mass of copper = 63.5

Atomic mass of sulphur = 32.

Atomic mass of oxygen = 16.

So molecular mass of copper sulphate = $63.5 + 32 + 4\times16$ = 159.5.

So, mass of 1 mole of copper sulphate is 159.5 grams.

So, in 31.9 grams of copper sulphate, number of moles of copper sulphate present = $\frac {159.5}{31.9}$ = 0.2

In 1 mole of copper sulphate, 1 mole of copper is present.

So in 0.2 moles of copper sulphate, 0.2 moles of copper is present.

So mass of 0.2 moles of copper = $0.2\times63.5$ = 12.7 grams

8 0

4 years ago

Propane burns in air to form water vapor and another gas. What is the volume of the water vapor at 500°C and 1 atm?

kakasveta [241]

Answer:

253.85 L

Explanation:

We'll begin by writing the balanced equation for the reaction. This is illustrated below:

C₃H₈ + 5O₂ —> 3CO₂ + 4H₂O

From the balanced equation above, 4 moles of water vapor were produced.

Finally, we shall determine the volume of the water vapor produced as follow:

Mole water vapor (n) = 4 moles

Pressure (P) = 1 atm

Temperature (T) = 500 °C = 500 °C + 273 = 773 K

Gas constant (R) = 0.821 atm.L/Kmol

Volume (V) =?

PV = nRT

1 × V = 4 ×0.0821 × 773

V = 253.85 L

Thus, the volume of water vapor obtained is 253.85 L

7 0

3 years ago

If you weighed out 0.38 g of calcium and reacted it with an excess of hcl, how many moles of h2(g) would you expect to produce?

Hitman42 [59]

Answer is: 0,0095 mol of hydrogen gas will be produced in reaction.
Chemical reaction: Ca + 2HCl → CaCl₂ + H₂.
m(Ca) = 0,38 g.
n(H₂) = ?
n(Ca) = m(Ca) ÷ M(Ca).
n(Ca) = 0,38 g ÷ 40 g/mol
n(Ca) = 0,0095 mol.
from reaction: n(Ca) : n(H₂) = 1 : 1.
n(H₂) = n(Ca) = 0,0095 mol.
n - amount of substance.

4 0

3 years ago

How could you ensure that all the spectroscopes used the same calibration line and equation? What would you need to be sure was

NISA [10]

People had asked this many times and that is why they came up with methods and standards that will answer these type of questions. You can look it up in the NIST or the National Institute for Standards and Technology.

8 0

3 years ago