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3 years ago

An element X that has 15 protons and 15 electrons, loses three

Chemistry

1 answer:

Wewaii [24]3 years ago

8 0

Answer:

12 electrons and 15 protons.

Explanation:

The element having 15 electrons and 15 protons have atomic number 15. We know that when an atom lose or gain the electron ions are formed.

Anion formation:

Anion is formed when electron is accept by an atom.

X + e⁻ → X⁻

Cation formation:

Cation is formed when electron lose be an atom.

X → X⁺ + e⁻

The given atom loses 3 electrons thus oxidation number will be +3 and cation is formed.

X → X³⁺ + 3e⁻

Now element X have 15 protons and 12 electrons.

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1.5g of magnesium ribbon is burnt in oxygen to produce 2.5g of magnesium oxide. How much oxygen is required in grams?

Furkat [3]

Answer:

2.5 grams

Explanation:

law of conservation of mass applies. the magnesium completely burns

4 0

3 years ago

What weight of sodium formate must be added to 4.00L of 1.00 M formic acid to produce a buffer solution that has a pH of 3.50?

tester [92]

Answer:

156,4 g of sodium formate

Explanation:

The pka of the formic acid is 3,74. Using Henderson-Hasselbalch formula:

pH = pka + log₁₀ [A⁻] / [HA] (1)

Where A⁻ is the conjugate base (Formate) and HA is the formic acid.

4.00L of 1.00M formic acid contain:

4.00L × (1.00mol /L) = 4.00 moles

Replacing these moles, the desired pH and the pka value in (1):

3,50 = 3,74 log₁₀ [A⁻] / 4,00 moles

-0,24 = log₁₀ [A⁻] / 4,00 moles

0,575 = [A⁻] / 4,00 moles

2,30 moles = [A⁻]

That means you need 2,30 moles of formate (Sodium formate), to produce the desired buffer. As the molar mass of sodium formate is 68,01g/mol, the weight of sodium formate that must be added is:

2,30mol×(68,01g/mol) = 156,4 g of sodium formate.

I hope it helps!

7 0

3 years ago

A. Directions:Describe ways on how to protect humans and plants and animals Choose your answer in the box and fill in the concep

Roman55 [17]

Answer:

i) Humans - drinks lot of water

- use umbrella

- use hats and sunglasses

- apply sunblock when swimming

- wear rush guard

ii) Plants - water the plants

-put a shade on the plants

iii) Animals - provide pets with plenty of water

- place the animals under the tree during noon time

3 0

3 years ago

Titration of 25.00 ml of an unknown hcl solution with 0.1550 m naoh starts at a buret reading for naoh of 0.33 ml. the phenolpht

Paul [167]

Q1)
NaOH solution is in the burette and called the titrant
HCl a known volume is in the titration flask and called the titrand.
initial burette reading of NaOH - 0.33 mL
final buretter reading of NaOH - 24.19 mL
therefore volume of NaOH added / dispensed - 24.19 - 0.33 = 23.86 mL
23.86 mL of NaOH was dispensed

Q2)
phenolphthalein is an acid base reaction indicator that shows a colour change from colourless in neutral and acidic media to pink colour in basic media.
phenolphthalein when added to the acid solution is colourless.
Once NaOH is added, OH⁻ reacts with H⁺ in acid and is neutralised. After all the H⁺ in medium is used up, the added OH⁻ is no longer neutralised.
in the presence of excess OH⁻, solution becomes basic and phenolphthalein becomes pink.
number of moles of NaOH = concentration x volume
number of NaOH moles = 0.1550 mol/L x (23.86 x 10⁻³ L) = 3.698 x 10⁻³ mol
NaOH moles added = 3.698 x 10⁻³ mol

Q3)

Neutralisation reaction is the reaction between an acid and base.
H⁺ ions of acid and OH⁻ ions of base react to form water and become neutralised.
when acid and base react they form water and salt.
the reaction is as follows;
HCl (aq) + NaOH (aq) --> NaCl (aq) + H₂O (l)

8 0

3 years ago

17.0cm

Mademuasel [1]

Answer:

24.68 g/cm³

Explanation:

We'll begin by calculating the volume of the marble. This can be obtained as follow:

Volume = 17 × 23 × 4

Volume = 1564 cm³

Next, we shall convert the mass of the marble (i.e 38.6 kg) to grams (g). This can be obtained as follow:

1 kg = 1000 g

Therefore,

38.6 kg = 38.6 kg × 1000 g / 1 kg

38.6 kg = 38600 g

Therefore, 38.6 kg mass of the marble slab is equivalent to 38600 g.

Finally, we shall determine the density of the marble slab as follow:

Volume = 1564 cm³

Mass = 38600 g.

Density =..?

Density = mass /volume

Density = 38600 g / 1564 cm³

Density = 24.68 g/cm³

Therefore, the density of the marble slab is 24.68 g/cm³

7 0

4 years ago