Answer:
Properties: The melting point of phosphorus (white) is 44.1°C, boiling point (white) is 280°C, specific gravity (white) is 1.82, (red) 2.20, (black) 2.25-2.69, with a valence of 3 or 5. There are four allotropic forms of phosphorus: two forms of white (or yellow), red, and black (or violet).Oct 7, 2019
Atomic Number: 15
Atomic Weight: 30.973762
Explanation:
: )
Answer:
2.64%
Explanation:
mass percent = (grams of solute / grams of solution) x 100
mass percent = (2.4 / 91) × 100
mass percent = 2.64% to 3sf
Answer: pure substances.
Explanation:
The given substances are:
All what surrounds us, which has mass and occupies spaces, is matter. There are two kind of matter: pure substances and mixtures.
Pure substances have a uniform and constant composition. On the other hand, mixtures are combinations of two or more pure substances in any arbitratry ratio.
Pure substances may be elements or compounds. The elements are the substances conmposed by one only kind of atom. In the list of substances given, Li and O₂ are elements: all the atoms in Li are lithium, and all the atoms in O₂ are oxygen atoms.
Compounds are the chemical combination of two or more different kind of atoms. In the given list H₂O₂ and NaCl are compounds. As you see, H₂O₂ contains atoms of hydrogen and oxygen, chemically bonded, in a fixed ratio (2 atoms of hydrogen by 2 atoms of oxygen). And NaCl has atoms of Na (sodium) and Cl (chlorine), chemicaly bonded, in a fixed ratio (1:1).
There are only 118 known elements and you can find them in any modern periodic table. Therer are virtually infinitely many compounds since many different combinations of the elements can be attained.
Elements and compounds have in common that they are classified as pure substances.
Answer:
There are many errors possible while titrating the acid of an unknown concentration with a base like NaOH.
Main error that leads to the error in results is misreading of the end point volume .
End point is when the reaction between the analyte and solution of known concentration has stopped .
Sometimes Burette is not straight enough to read the volume of the end point. One way to misread the volume of burette is by looking at the burette volume at an angle .
From above , volume seems to be higher. Indicators are used to indicate the color change of the reaction. In Acid-Base titrations , indicators first lighten up then changes its color.
So, error may have occurred in wrongly judging of the end point by color change of the indicator .
