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4 years ago

Is brass an elements please? Thanks!

2 answers:

8 0

The material, Brass is not an element. The different elements can be seen on the periodic table. Anyway, brass is an alloy of metal. Although, gold, silver, copper and many others are elements. Hope i helped. Have a nice day.

VladimirAG [237]4 years ago

6 0

Brass is NOT an element, it's a mixture metals. We call it an alloy.

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Gold has a molar (atomic) mass of 197 g/mol. consider a 2.47 g sample of pure gold vapor. (a) calculate the number of moles of g

adell [148]

N = given mass/ molar mass.
n = number of moles
given mass = 2.47 g
molar mass = 197 g/mol

n = 2.47 / 197
n = 0.01253 moles.
I'm sure you wanted to ask more than this. Just put some comments in. I can do the same.

3 0

3 years ago

Proportional means that

FromTheMoon [43]

Corresponding in size or amount to something else.

5 0

3 years ago

1-Propynyllithium reacts with (R,R)-2,3-dimethyloxacyclopropane in a stereoselective reaction. Draw a curved arrow mechanism and

QveST [7]

Answer:

Reference image attached

Explanation:

Please see the attached image.

6 0

3 years ago

What is the pH of a mixture of 0.042 M NaH2PO4 and 0.058 M Na2HPO4? Hint: The pKa of phosphate is 6.86.

AlekseyPX

Answer:

The pH value of the mixture will be 7.00

Explanation:

Mono and disodium hydrogen phosphate mixture act as a buffer to maintain pH value around 7. Henderson–Hasselbalch equation is used to determine the pH value of a buffer mixture, which is mathematically expressed as,

$pH=pK_{a} + log(\frac{[Base]}{[Acid]})$

According to the given conditions, the equation will become as follow

$pH=pK_{a} + log(\frac{[Na_{2}HPO_{4} ]}{[NaH_{2}PO_{4}]})$

The base and acid are assigned by observing the pKa values of both the compounds; smaller value means more acidic. NaH₂PO₄ has a pKa value of 6.86, while Na₂HPO₄ has a pKa value of 12.32 (not given, but it's a constant). Another more easy way is to the count the acidic hydrogen in the molecular formula; the compound with more acidic hydrogens will be assigned acidic and vice versa.

Placing all the given data we obtain,

$pH=6.86 + log(\frac{0.058}{0.042})$

$pH=7.00$

5 0

4 years ago

Which of dalton's postulates about atoms are inconsistent with later observations? do these inconsistencies mean that dalton was

Neporo4naja [7]

1) Dalton stated that atom is matter that can not be divided, but it is proved that the atom can be divided into subatomic particles (electrons, protons and neutrons).

2) He stated that atoms of one element can not be changed into atoms of other elements, but now that is possible by nuclear reactions.

Today we still use his postulate: Atoms combine in the ratio of small whole numbers to form stable compounds, for example H₂O.

6 0

3 years ago