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4 years ago

What are the five rules for significant figures? Give some examples

1 answer:

4 0

"There are three rules on determining how many significant figures are in a number: Non-zero digits are always significant. Any zeros between two significant digits are significant. A final zero or trailing zeros in the decimal portion ONLY are significant."

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12 points

Ad libitum [116K]

Answer:

C₅H₈O₂

Explanation:

methyl methacrylate = 100 amu

6.91g CO₂ = 0.157 moles

2.26g H₂O = 0.125 moles

0.157 ÷ 0.125 = 1.256

{(CO₂)₁.₂₅₆ + (H₂O)₁} × 4 = (CO₂)₅ + (H₂O)₄

C₅H₈O?

C₅ = 60.05 amu H₈ = 8.064 amu

60.05 + 8.064 = 68.114 amu

100 amu - 68.114 amu = 31.886 amu

O = 16 amu

O = 2

8 0

3 years ago

When of glycine are dissolved in of a certain mystery liquid , the freezing point of the solution is lower than the freezing poi

Nesterboy [21]

The given question is incomplete. The complete question is:

When 282. g of glycine (C2H5NO2) are dissolved in 950. g of a certain mystery liquid X, the freezing point of the solution is 8.2C lower than the freezing point of pure X. On the other hand, when 282. g of ammonium chloride are dissolved in the same mass of X, the freezing point of the solution is 20.0C lower than the freezing point of pure X. Calculate the van't Hoff factor for ammonium chloride in X.

Answer: the van't Hoff factor for ammonium chloride is 1.74

Explanation:

Depression in freezing point is given by:

$\Delta T_f=i\times K_f\times m$

$\Delta T_f=T_f^0-T_f=8.2^0C$ = Depression in freezing point

$K_f$ = freezing point constant = ?

i = 1 ( for non electrolyte)

m= molality

$8.2^0C=1\times K_f\times \frac{\text{mass of solute}}{\text{molar mass of solute}\times \text{weight of solvent in kg}}$

Weight of solvent (X)= 950 g = 0.95 kg

Molar mass of solute (glycine) = 75.07 g/mol

Mass of solute (glycine) = 282 g

$8.2^0C=1\times K_f\times \frac{282g}{75.07g/mol\times 0.95kg}$

$K_f=2.07$

ii) $20.0^0C=i\times \times \frac{\text{mass of solute}}{\text{molar mass of solute}\times \text{weight of solvent in kg}}$

Weight of solvent (X)= 950 g = 0.95 kg

Molar mass of solute (ammonium chloride) = 53.49 g/mol

Mass of solute (ammonium chloride) = 282 g

$20.0^0C=i\times 2.07\times \frac{282g}{53.49g/mol\times 0.95kg}$

$i=1.74$

Thus the van't Hoff factor for ammonium chloride is 1.74

4 0

3 years ago

How are we made of the same atoms in stars?

MariettaO [177]

Stardust atoms are heavier elements, the percentage of star mass in our body is much more impressive. Most hydrogen in our body floats around in the form of water .

3 0

4 years ago

Distinguish between single and double replacement reactions and give an example of<br> each.

Alenkasestr [34]

Answer:

i think this is right!

Explanation:

An example of a single replacement reaction occurs when potassium (K) reacts with water (H2O). A colorless solid compound named potassium hydroxide (KOH) forms, and hydrogen gas (H2) is set free. The equation for the reaction is: 2K + 2H2O → 2KOH + H.

An example of a double replacement reaction is the reaction between silver nitrate and sodium chloride in water. Both silver nitrate and sodium chloride are ionic compounds. Both reactants dissolve into their ions in aqueous solution.

6 0

2 years ago

A carbon atom has six electrons. How are these electrons shared in its atomic orbital shells?

umka21 [38]

The correct response is A. The inner she'll contains 2 electrons and the outer shell contains 4 electrons.

6 0

4 years ago

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