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german
4 years ago
7

During a lab activity, students prepared two solutions separately at the same temperature. Later they mixed the solutions and th

e temperature dropped. Why?
Chemistry
1 answer:
tino4ka555 [31]4 years ago
7 0
This at be due to a chemical change. For example, when some chemical elements mix, the change causes heat. This is the same, but the opposite. Hope this helps!
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In a water molecule, two hydrogen atoms bind to one oxygen atom. How many lone pairs of electrons will be shown around each hydr
anzhelika [568]
There are no lone pair of electrons shown around the hydrogen atoms, rather there are 2 lone election pairs present around the central atom in this Lewis structure and that is Oxygen. Hydrogen only has bonding electrons, and it requires 2 electrons per hydrogen to achieve stability and have a full valence electron shell.
5 0
4 years ago
Read 2 more answers
Generally how does the first ionization energy vary as the atomic number increases going across a period
Vlad1618 [11]

Across a period I.E increases progressively from left to right

Explanation:

The trend of the first ionization energy is such that across a period I.E increases from left to right due to the decreasing  atomic radii caused by the increasing nuclear charge. This not compensated for by successive electronic shells.

  • Ionization energy is a measure of the readiness of an atom to lose an electron.
  • The lower the value, the easier it is for an atom to lose an electron.
  • Elements in group I tend to lose their electrons more readily whereas the halogens hold most tightly to them.
  • The first ionization energy is the energy needed to remove the most loosely bonded electron of an atom in the gaseous phase.

Learn more:

Ionization energy brainly.com/question/6324347

#learnwithBrainly

3 0
4 years ago
Which of the following equalities is not correct?
Kryger [21]

1cm^3 = 1L would be the correct answer. One cubic centimeter equals .001 liter, so this equality above is not correct.

Please let me know if you have any questions! :)

8 0
3 years ago
Read 2 more answers
The amount ofcalcium present in milk can be determined by adding oxalate to asample and measuring the massof calcium oxalate pre
Sauron [17]

<u>Answer:</u> The mass percent of calcium in milk is 0.107 %

<u>Explanation:</u>

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
3 years ago
An aqueous solution of barium hydroxide is standardized by titration with a 0.102 M solution of perchloric acid. If 10.3 mL of b
Vesna [10]

<u>Answer:</u> The molarity of barium hydroxide solution is 0.118 M.

<u>Explanation:</u>

To calculate the concentration of acid, we use the equation given by neutralization reaction:

n_1M_1V_1=n_2M_2V_2

where,

n_1,M_1\text{ and }V_1 are the n-factor, molarity and volume of acid which is HClO_4

n_2,M_2\text{ and }V_2 are the n-factor, molarity and volume of base which is Ba(OH)_2

We are given:

n_1=1\\M_1=0.102M\\V_1=24.0mL\\n_2=2\\M_2=?M\\V_2=10.3mL

Putting values in above equation, we get:

1\times 0.102\times 24.0=2\times M_2\times 10.3\\\\M_2=0.118M

Hence, the molarity of Ba(OH)_2 solution will be 0.118 M.

6 0
3 years ago
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