Gr6_Sci_Assesment\FY18

Chemistry

1 answer:

Rzqust [24]3 years ago

5 0

Answer:

A. The student did not include the effect of friction in his calculation.

Explanation:

They are not equal because kinetic energy is relative to the state of other objects in its environment such as friction which doesn't apply to potential energy.

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One way of obtaining pure sodium carbonate is through the decomposition of the mineral trona, Na3(CO3)(HCO3)·2H2O. 2Na3(CO3)(HCO

zhenek [66]

Percentage yield = (actual yield / theoretical yield) x 100%

The balanced equation for the decomposition is,
2Na₃(CO₃)(HCO₃)·2H₂O(s) → 3Na₂CO₃(s) + CO₂(g) + 5H₂O(g)

The stoichiometric ratio between Na₃(CO₃)(HCO₃)·2H₂O(s) and Na₂CO₃(s) is 2 : 3

The decomposed mass of Na₃(CO₃)(HCO₃)·2H₂O(s) = 1000 kg
= 1000 x 10³ g

Molar mass of Na₃(CO₃)(HCO₃)·2H₂O(s) = 226 g mol⁻¹
moles of Na₃(CO₃)(HCO₃)·2H₂O(s) = mass / molar mass
= 1000 x 10³ g / 226 g mol⁻¹
= 4424.78 mol

Hence, moles of Na₂CO₃ formed = 4424.78 mol x $\frac{3}{2}$
= 6637.17 mol

Molar mass of Na₂CO₃ = 106 g mol⁻¹

Hence, mass of Na₂CO₃ = 6637.17 mol x 106 g mol⁻¹
= 703540.02 g
= 703.540 kg

Hence, the theoretical yield of Na₂CO₃ = 703.540 kg
Actual yield of Na₂CO₃ = 650 kg

Percentage yield = (650 kg / 703.540 kg) x 100%
= 92.34%

7 0

3 years ago

Convert 22 ml in to liters

prisoha [69]

Answer:

0.022

Explanation:

milliter (ml) = 1 cubic centimeter (cc)= 0.001 liters (l) = 0.000001 cubic meters (m3).

1 ml = 0.061024 cubic inches (in3) ; 1 in3 = 16.4 ml.

1 ml = 0.000035 cubic feet (ft3); 1 ft3 = 28,317 ml.

1 ml = 2.64 x 10-4 U.S. gallons (gal); 1 gal = 4.55 x 103 ml.

8 0

3 years ago

PLZ HELP, GIVING BRAINLIEST!!

Veseljchak [2.6K]

Answer:

2.29 moles of Cr₂O₃ are produced

Explanation:

This is the reaction:

4 Cr + 3O₂ → 2Cr₂O₃

Ratio for this equation is 4:2, so 4 moles of chromium can produce the half of moles of chromium(III) oxide

4.58 mol of Cr may produce (4.58 .2)/4 = 2.29 moles of Cr₂O₃

4 0

3 years ago

On molecular level what I causing the glaciers to melt

MakcuM [25]

Glaciers capture large amount of carbon dioxide from atmosphere. When concentration of carbon dioxide molecules in glaciers increase, then strength and fracture toughness of ice are decreased and that make glaciers vulnerable to cracking and splitting into fragments.
That is because hydrogen bonds between water molecules in glaciers is decreased under increasing concentrations of carbon dioxide who competes with the water molecules connected in the ice crystal.

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3 years ago

A student throws a 2kg ball at 4m/s. What is the ball’s momentum?

Vsevolod [243]

The answer is 8 m/s2

4 0

3 years ago