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xxMikexx [17]
3 years ago
14

Earths rotation takes about __________, whereas its revolution takes about _______.

Chemistry
1 answer:
Sergio [31]3 years ago
8 0
A.) a rotation is the earth "rotating" on its axis while a revolution is the earth "revolving" around the sun so 1 rotation is from sun rise to sun rise while one revolution is from January 1st to the next January 1st
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Write the symbols for the following isotopes: Its atoms contain 50 electrons and 70 neutrons
Veronika [31]
Since this element has 50 electrons you know that it has 50 protons. The number of proton= the atomic number. Atomic number 50 is tin. The atomic symbol for tin is Sn and the weight is 120. So this is the tin 120 isotope
6 0
3 years ago
How much heat must be removed from 456 g of water at 25.0°c to change it into ice at?
N76 [4]
This question can be simply solved by using heat formula,
    Q = mCΔT

Q = heat energy (J)
m = Mass (kg)
C = Specific heat capacity (J / kg K)
ΔT = Temperature change (K)

when water freezes, it produces ice at 0°C (273 K)
hence the temperature change is 25 K (298 K - 273 K)
C for water is 4186 J / kg K or 4.186 J / g K
By applying the equation,
 Q = 456 g x 4.186 J / g K x 25 K
     = 47720.4 J
     = 47.72 kJ

hence 47.72 kJ of heat energy should be removed.
5 0
3 years ago
if the percent by volume is 2% and the volume of solution is 250 mL what is the volume of solute and solution
Liula [17]

Answer:

Solute = 5 mL; solution = 250 mL  

Explanation:

The formula for percent by volume is

\text{Percent by volume} = \dfrac{\text{Volume of solute}}{\text{Volume of solution}}\times 100 \, \%

If you have 250 mL of a solution that is 2 % v/v,

\begin{array}{rcl}2 \, \% & = & \dfrac{\text{Volume of solute}}{\text{250 mL}}\times 100 \, \%\\\\2 \times \text{ 250 mL} & = & \text{Volume of solute} \times 100\\\text{Volume of solute} & = & \dfrac{2 \times 250\text{ mL}}{100}\\\\ & = & \textbf{5 mL}\\\end{array}

If there is no change of volume on mixing,

Volume of solution = 250 mL

 -Volume of solute = <u>     </u><u>5</u><u>      </u>

 Volume of solvent = 245 mL

5 0
3 years ago
Find the ph of a 0.250 m solution of nac2h3o2. (the ka value of hc2h3o2 is 1.80×10−5). express your answer numerically to four s
Slav-nsk [51]
Answer is: pH value of solution of NaC₂H₃O₂ is 9.07.
Chemical reaction: C₂H₃O₂⁻ + H₂O ⇄ HC₂H₃O₂ + OH⁻.
Ka(HC₂H₃O₂) = 1,8·10⁻⁵.<span>
Ka · Kb = Kw.
</span>1,8·10⁻⁵ mol/dm³ · Kb = 1·10⁻¹⁴ mol²/dm⁶; the ionic product of water at 25°C.<span>
Kb(</span>C₂H₃O₂⁻) = 1·10⁻¹⁴ mol²/dm⁶ ÷ 1,8·10⁻⁵ mol/dm³.<span>
Kb(</span>C₂H₃O₂⁻) = 5,56·10⁻¹⁰ mol/dm³.
c(C₂H₃O₂⁻) = 0,25 M.
[OH⁻] = [HC₂H₃O₂] = x.
[C₂H₃O₂⁻] = 0,25 M - x.
Kb = [OH⁻] · [HC₂H₃O₂] / [C₂H₃O₂⁻].
5,56·10⁻¹⁰ = x² / (0,25 M -x).
Solve quadratic equation: x = [OH⁻] = 0,0000118 M.
pOH = -log[OH⁻] = -log(0,0000118M) = 4,93.
pH + pOH = 14.
pH = 14 - 4,93 = 9,07.
6 0
3 years ago
How does the number of reactants in a double-displacement reaction
mojhsa [17]
In a typical double displacement reaction, you would have a total of two products (AB + CD —> AD + BC).
5 0
2 years ago
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