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-BARSIC- [3]
2 years ago
8

Please help this is on my exam

Chemistry
1 answer:
Vikentia [17]2 years ago
6 0

Answer:

D. The time of day

Explanation:

The independent variable is the variable the experimenter changes or controls and is assumed to have a direct effect on the dependent variable

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What is the effect of an insoluble impurity, such as sand, on the observed melting point of a compound?]?
Taya2010 [7]
The effect of an insoluble impurity, such as sand, on the observed melting point of a compound would be none. It will not depress or elevate the melting point of the compound. Instead, it would affect the reading if you are trying to determine the melting point of the compound. This is because you might be missing  the actual melting point of the compound since you will be waiting for the whole sample to liquify. You would not be able to determine exactly that temperature because of the insoluble impurity would have a different melting point than that of the compound.
7 0
3 years ago
Does anyone know the answer to these?
Rashid [163]

Answer:

The answer to your question is below

Explanation:

Data

mass of CaCO₃ = 155 g

mass of HCl = 250 g

mass of CaCl₂ = 142 g

reactants = CaCO₃ + HCl

products = CaCl₂ + CO₂ + H₂O

1.- Balanced chemical reaction

             CaCO₃ + 2HCl   ⇒    CaCl₂ + CO₂ + H₂O

2.- Limiting reactant

molar mass of CaCO₃ = 40 + 12 + 48 = 100 g

molar mass of HCl = 2[1 + 35.5 ] = 73 g

theoretical proportion CaCO₃ /HCl = 100 / 73 = 1.37

experimental proportion CaCO₃ /HCl = 155 / 250 = 0.62

As the experimental proportion was lower than the theoretical proportion the limiting reactant is CaCO₃

3.-

Calculate the molar mass of CaCl₂

CaCl₂ = 40 + 71 = 111 g

          100 g of CaCO₃ ------------------ 111 g of CaCl₂

           155 g of CaCO₃ ----------------- x

               x = (155 x 111) / 100

               x = 17205 / 100

              x = 172.05 g of CaCl₂

4.- percent yield

Percent yield = 142 / 172.05 x 100 = 82.5 %

5.- Excess reactant

    100 g of CaCO₃  -------------------- 73 g of HCl

     155 g of caCO₃ ------------------- x

           x = (155 x 73)/100

           x = 133.15 g

Mass of HCl = 250 - 133.15

                    = 136.9 g

4 0
3 years ago
Very small particles of solids and liquids suspended in air are called​
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Answer: Very small fragments of solid materials or liquid droplets suspended in air are called particulates. ... For example, solid particulates between roughly 1 and 100 μm in diameter are called dust particles, whereas airborne solids less than 1 μm in diameter are called fumes.

Brainliest would be nice!

Explanation:

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2 years ago
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Which metal pan should the chef choose because it undergoes the largest temperature change for a given input of energy?
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If the chef is in a hurry we would assume he would want the pan to heat up so copper

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1 know

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