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2 years ago

A factor that changes in an experiment from manipulation of the independent variable is the what?

1 answer:

7 0

Manipulation of the independent variable should change the dependent variable, the value of which "depends" on the independent variable's change in value.

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The amount ofcalcium present in milk can be determined by adding oxalate to asample and measuring the massof calcium oxalate pre

Sauron [17]

Answer: The mass percent of calcium in milk is 0.107 %

Explanation:

To calculate the number of moles, we use the equation:

$\text{Number of moles}=\frac{\text{Given mass}}{\text{Molar mass}}$ .....(1)

Given mass of calcium oxalate = 0.429 g

Molar mass of calcium oxalate = 128.1 g/mol

Putting values in equation 1, we get:

$\text{Moles of calcium oxalate}=\frac{0.429g}{128.1g/mol}=0.0033mol$

The given chemical equation follows:

$Na_2C_2O_4(aq.)+Ca^{2+}(aq.)\rightarrow CaC_2O_4(s)+2Na^+(aq.)$

Sodium oxalate is present in excess. So, it is considered as an excess reagent. And, calcium ion is a limiting reagent because it limits the formation of product.

By Stoichiometry of the reaction:

1 mole of calcium oxalate is produced from 1 mole of calcium ion

So, 0.0033 moles of calcium oxalate is produced from = $\frac{1}{1}\times 0.0033=0.0033mol$ of calcium ions

Now, calculating the mass of calcium ions by using equation 1, we get:

Moles of calcium ions = 0.0033 moles

Molar mass of calcium ions = 40 g/mol

Putting values in equation 1, we get:

$0.0033mol=\frac{\text{Mass of calcium ions}}{40g/mol}\\\\\text{Mass of calcium ions}=(0.0033mol\times 40g/mol)=0.132g$

To calculate the mass percentage of calcium ions in milk, we use the equation:

$\text{Mass percent of calcium ions}=\frac{\text{Mass of calcium ions}}{\text{Mass of milk}}\times 100$

Mass of milk = 125 g

Mass of calcium ions = 0.132 g

Putting values in above equation, we get:

$\text{Mass percent of calcium ions}=\frac{0.132g}{125g}\times 100=0.107\%$

Hence, the mass percent of calcium in milk is 0.107 %

7 0

2 years ago

What happens to the electron cloud at very high atomic numbers, when the innermost electrons would, using a non-relativistic mod

marin [14]

Answer:

tough question

Explanation:

8 0

1 year ago

What happens when an atom of sulfur combines with two atoms of chlorine to produce SCI2?

Aloiza [94]

Answer:..A.) Each chlorine atom shares a pair of electrons with the sulfur atom

3 0

1 year ago

1. Who is the father of atomic theory? 2. Who discovered the electron? 3. Who expressed particles by wave equations? 4. Who rese

krek1111 [17]

1. Who is the father of atomic theory?
Dalton

2. Who discovered the electron?
Thomson

3. Who expressed particles by wave equations?
Schrödinger

4. Who researched on radioactivity?
Curie

5. Who discovered the "open spaces" model?
Rutherford

6. Who applied quantum theory to atoms?
Bohr

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3 years ago

Read 2 more answers

Convert 55.6 km to m show equation

crimeas [40]

Explanation:

1 km = 1000m

55.6 km = x m

x = 55.6*1000

x = 55600m

5 0

3 years ago

Read 2 more answers