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2 years ago

On the periodic table, calcium is in group 2. What is true about calcium?

Chemistry

1 answer:

Ray Of Light [21]2 years ago

6 0

Answer:

Explanation:

Calcium is all around us. The average human contains approximately 1kg of calcium, of which 99% is stored in our bones. It is the 5th most abundant element in the earth's crust, occurring widely as calcium carbonate which is more commonly known as limestone. It is also the fifth most abundant dissolved ion in seawater.

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Which type of radiation involves the conversion of a neutron into a proton?

romanna [79]

Answer:

B. Beta

Explanation:

Neutron -> proton = responsible by Beta particles.

3 0

1 year ago

A cheeseburger from a fast food restaurant contains 19 g of fat, 20 g of carbohydrate, and 28 g of protein. how many kcal of ene

Burka [1]

I believe the answer is D

3 0

2 years ago

Write balance complete molecular equation, ionic equation, and net ionic equations for the reactions that occur when each of the

AveGali [126]

Answer: The complete molecular, ionic, and net ionic equations are given below. The spectator ions are sodium and nitrate ions.

Explanation:

The ionic equation is defined as the equation in which all the substances that are strong electrolytes present in an aqueous state and are represented in the form of ions.

The net ionic equation is defined as the equations in which spectator ions are not included.

Spectator ions are the ones that are present equally on the reactant and product sides. They do not participate in the reaction.

The balanced molecular equation for the reaction of lead (II) nitrate and sodium sulfide follows:

$Pb(NO_3)_2(aq)+Na_2S(aq)\rightarrow PbS(s)+2NaNO_3(s)$

The ionic equation follows:

$Pb^{2+}(aq)+2NO_3^-(aq)+2Na^+(aq)+S^{2-}(aq)\rightarrow PbS(s)+2Na^+(aq)+2NO_3^-(aq)$

As sodium and nitrate ions are present on both sides of the reaction. Thus, they are considered spectator ions.

The net ionic equation follows:

$Pb^{2+}(aq)+S^{2-}(aq)\rightarrow PbS(s)$

3 0

2 years ago

A radioactive nucleus alpha decays to yield a sodium-24 nucleus in 14.8 hours. What was the identity of the original nucleus?

Rudik [331]

Answer:

2813Al

Explanation:

You know that alpha decay takes place when a α-particle is being ejected from the nucleus of a radioactive isotope.An

α-particle is simply the nucleus of a helium-4 atom. A helium-4 atom has a total of two protons and two neutrons in its nucleus, and two electrons surrounding that nucleus.

In that case, if a α-particle is the nucleus of a helium-4 atom, then it must have a mass number equal to 4, since it has two protons and two neutrons, and a net charge of (2+) since it no longer has the two electrons that the helium-4 atom has.

So, you know that an unknown radioactive isotope decays via alpha decay to yield a sodium-24 nucleus.

A sodium-24 nucleus contains 11 protons and 13 neutrons. This means that you can write

AZX→2411Na+42α

Here A and Z represent the unknown element's mass number and atomic number, respectively.

So, if you take into account the fact that mass number and atomic number must be conserved in a nuclear reaction, you can say that

A=24+4 and Z=11+2

The unknown isotope will thus have

{A=28Z=13

A quick look at the periodic table will show you that the element that has 13 protons in its nucleus is aluminum, Al. This means that you're dealing with aluminum-28, an isotope of aluminum that has 15 neutrons in its nucleus.

The complete nuclear equation will be

2813Al→2411Na+42α

5 0

3 years ago

The characteristic odor of pineapple is due to ethyl butyrate, a compound containing carbon, hydrogen, and oxygen. combustion of

aev [14]

Answer: C₃H₆O

Explanation:

1) First, calculate the chemical composition, which you do using balance mass using the data given.

2) Data:

i) mass of ethyl butyrate: 2.22 mg

ii) mass of CO₂: 5.06 mg

iii) mass of H₂O: 2.06 mg

3) Solution

i) All the carbon in CO₂ produced was present in the ehtyl butyrate sample.

ii) The molar mass of CO₂ is 44.01 g/mol

iii) Use proportionality:

12.01 g C / 44.01 g CO₂ = x / 5.06 mg C ⇒ x = 1.38 mg C

iv) All the H in H₂O was present in the original sample of ethyl butyrate

v) The molar mass of H₂O is 18.015 g/mol

vi) Use proportionality

2.016 g H / 18.015 g H₂O = x / 2.06 mg H ⇒ x = 0.23 mg H

vii) Mass balance:

mass of O in the sample = mass of the sample - mass of H - mass of C

mass of O = 2.22 mg - 1.38 mg - 0.23 mg = 0.61 mg O.

viii) Composition:

C = 1.38 mg

H = 0.23 mg

O = 0.61 mg

Which in terms of composition is the same that:

C = 1.38 g

H = 0.23 g

O = 0.61 g

ix) Divide each by the molar atomic mass of the corresponding element, to obtain the number of moles:

C = 1.38 g / 12.01 g/mol = 0.115 mol

H = 0.23 g / 1.008 g/mol = 0.228 mol

O = 0.61 g / 16 g/mol = 0.0381 mol

x) Divide each by the least number of moles to obtain mole proportion

C = 0.115 / 0.0381 = 3.02 ≈ 3

H = 0.228 / 0.0381 = 1.98 ≈ 5.98 ≈ 6

O = 0.0381 / 0.0381 = 1

xi) Therefore the empirical formula searched is C₃H₆O.

7 0

2 years ago