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3 years ago

Why is carbon used to date things that were once living?

Chemistry

1 answer:

Oliga [24]3 years ago

6 0

Explanation:

Because carbon-14 decays at this constant rate, an estimate of the date at which an organism died can be made by measuring the amount of its residual radiocarbon. ... The carbon-14 method was developed by the American physicist Willard F.

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Answer me fast!

Ede4ka [16]

Distance and time is needed for determining speed

8 0

3 years ago

Urgent!! A chemist measured 5.2 g copper(II) bromide tetrahydrate (CuBr2•4(H2O)). How many moles were measured out? Answer in un

bezimeni [28]

The moles which were measured out is calculated using the following formula

moles = mass/molar mass

molar mass of CuBr2.4H20 = 63.5 Cu + ( 2 x79.9) br + ( 18 x4_) h20 = 295.3 g/mol

moles is therefore= 5.2 g/ 295.3 g/mol= 0.0176 moles

4 0

2 years ago

Read 2 more answers

A chemist determines by measurements that 0.0550 moles of nitrogen gas participate in a chemical reaction. Calculate the mass of

shtirl [24]

The mass of nitrogen gas that participated in the chemical reaction is 1.54g

HOW TO CALCULATE MASS OF AN ELEMENT:

Mass of a substance can be calculated by multiplying the number of moles in mol of the substance by its molecular mass in g/mol. That is;

mass (M) = molar mass (MM) × number of moles (n)

According to this question, a chemist determines by measurements that 0.0550 moles of nitrogen gas (N2) participate in a chemical reaction.

The molecular mass of nitrogen gas (N2) = 14.01(2)

= 28.02g/mol

Hence, the mass of the nitrogen gas that participated in the chemical reaction is calculated as follows:

Mass (g) = 0.0550 mol × 28.02 g/mol

Mass = 1.5411

Therefore, the mass of nitrogen gas that participated in the chemical reaction is 1.54g

Learn more: brainly.com/question/18269198

6 0

2 years ago

Complete the hybridization and bonding scheme for xef4.

Vikentia [17]

<span>Xe = VIII = 8 valence electrons
F = VII = 4 (7 ve) = 28 valence electrons</span>

total ve = 8 + 28 = 36 ve

<span>36 - 4(2) = 28 ve
(there are 2 electrons in each bond x 4 bonds)</span>

<span>28 - 4(6) = 4
(We assign the remaining electrons to F atoms)</span>

<span>4 - 2(2) = 0
(Therefore 4 electrons left => we have 2 lone pairs)</span>

The steric number = No. of σ bonds + #lone pairs

= 4 σ bonds + 2 lone pairs = 6 => d²sp³ (6 hybrid orbitals)

<span>4 bonds + 2 lone pairs => square planar</span>

6 0

3 years ago

6. How many moles of water would require 92.048 kJ of heat to raise its temperature from 34.0 °C to 100.0 °C? (3 marks)

scoray [572]

Taking into account the definition of calorimetry, 0.0185 moles of water are required.

<h3>Calorimetry</h3>

Calorimetry is the measurement and calculation of the amounts of heat exchanged by a body or a system.

Sensible heat is defined as the amount of heat that a body absorbs or releases without any changes in its physical state (phase change).

So, the equation that allows to calculate heat exchanges is:

Q = c× m× ΔT

where Q is the heat exchanged by a body of mass m, made up of a specific heat substance c and where ΔT is the temperature variation.

<h3>Mass of water required</h3>

In this case, you know:

Heat= 92.048 kJ
Mass of water = ?
Initial temperature of water= 34 ºC
Final temperature of water= 100 ºC
Specific heat of water = 4.186 $\frac{J}{gC}$

Replacing in the expression to calculate heat exchanges:

92.048 kJ = 4.186 $\frac{J}{gC}$ × m× (100 °C -34 °C)

92.048 kJ = 4.186 $\frac{J}{gC}$ × m× 66 °C

m= 92.048 kJ ÷ (4.186 $\frac{J}{gC}$ × 66 °C)

<u><em>m= 0.333 grams</em></u>

<h3>Moles of water required</h3>

Being the molar mass of water 18 $\frac{g}{mole}$ , that is, the amount of mass that a substance contains in one mole, the moles of water required can be calculated as: