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Gekata [30.6K]
3 years ago
7

Sarah heated some orange coloured crystals in a test tube. The crystals turned green and fizzed. After the fizzing stopped, the

test tube was allowed to cool. A green powder was left in the tube. Determine whether a chemical or a physical reaction has occurred. Identify two observations that support your decision.
Chemistry
1 answer:
Anni [7]3 years ago
6 0
A chemical change has occurred.
This is indicated by a colour change occurring (from orange to green) as well as a gas being given off (seen as the fizzing). If the fizzing made a small amount of noise, it also indicates that sound energy is given off, which is another indication that a chemical reaction has occurred.
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Why do atoms of elements take part in chemical reaction?​
Marina CMI [18]

Explanation:

During a chemical reaction, the atoms of the original substances gain, lose or share their electrons with those of the substances with which they are reacting. The reaction creates new substances made up of a new combination of atoms and a different configuration of electrons.

4 0
3 years ago
The graph below shows the volume and the mass of four different substances at STP.
sladkih [1.3K]
The formula of density is mass / volume

This means that
- high mass, low volume = high density
- high mass, high volume = so-so
- low mass, high volume = low density

From the graph shown, 
D has the lowest density because it has low mass yet high volume.
6 0
4 years ago
What information does a molecular formula give?
Leokris [45]

Answer:

A. The actual number of atoms in a molecule

Explanation:

Molecular formula is simply defined as a type of chemical formula that describes the type and number of atoms present in a single molecule of a compound.

Looking at the options, the correct answer is option A.

5 0
3 years ago
Read 2 more answers
Sodium metal is sometimes used as a cooling agent in heat exchange units because of its relatively high molar heat capacity of 2
IgorC [24]

Answer:

The specific heat of sodium is 1,23J/g°C

Explanation:

Using the atomic weight of sodium (23g/mol) and the atomic weight definition, we have that each mole of the substance has 23 grams of sodium.

starting from this, we use the atomic weight of sodium to convert the units from J / mol ° C to J / g ° C

28,2 \frac{J}{mol C} x \frac{1mol}{23g} = 1,23 J/g C

4 0
3 years ago
How many hydrogen atoms are in 35.0 grams of hydrogen gas? How many hydrogen atoms are in 35.0 grams of hydrogen gas? 4.25 × 102
Ede4ka [16]

Answer: 2.12\times 10^{25} atoms of hydrogen are there in

35.0 grams of hydrogen gas.

Explanation:

According to avogadro's law, 1 mole of every substance occupies 22.4 L at STP and contains avogadro's number 6.023\times 10^{23} of particles.

To calculate the moles, we use the equation:

\text{Number of moles}=\frac{\text{Given mass}}{\text {Molar mass}}=\frac{35.0g}{2g/mol}=17.5moles

1 mole of hydrogen (H_2) = 2\times 6.023\times 10^{23}=12.05\times 10^{23} atoms

17.5 mole of hydrogen (H_2) = \frac{12.05\times 10^{23}}{1}\times 17.5=2.12\times 10^{25} atoms

There are 2.12\times 10^{25} atoms of hydrogen are there in

35.0 grams of hydrogen gas.

8 0
3 years ago
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