A0.1 mm sample of human blood has approximately 6000 red blood cells. an adult typically has 5.0 l of blood. how many red blood cells are in an adult? (1 ml = 1 cc). use "e" for scientific notation.

 3.0 × 10¹¹ RBC's    (or)      3E11 RBC's

Solution:

Step 1: Convert mm³ into L;

As,

                                            1 mm³  =  1.0 × 10⁻⁶ Liters

So,

                                         0.1 mm³  =  X  Liters

Solving for X,

                       X  =  (0.1 mm³ × 1.0 × 10⁻⁶ Liters) ÷ 1 mm³

                       X  =  1.0 × 10⁻⁷ Liters

Step 2: Calculate No. of RBC's in 5 Liter Blood:

As given

                        1.0 × 10⁻⁷ Liters Blood contains  =  6000 RBC's

So,

                         5.0 Liters of Blood will contain  =  X  RBC's

Solving for X,

                      X  =  (5.0 Liters × 6000 RBC's) ÷ 1.0 × 10⁻⁷ Liters

                      X  =  3.0 × 10¹¹ RBC's

Or,

                     X  =  3E11 RBC's

when 25.0 ml of 0.700 mol/l naoh was mixed in a calorimeter with 25.0 ml of 0.700 mol/l hcl, both initially at 20.0 °c, the temperature increased to 22.1 °c. the heat capacity of the calorimeter is 279 j/°c.

the equation for the reaction is:

naoh + hcl → nacl + h₂o

moles of hcl = 0.0250 l hcl ×

0.700

mol hcl

1 l hcl = 0.0175 mol hcl

volume of solution = (25.0 + 25.0) ml = 50.0 ml

mass of solution = 50.0 ml soln ×

1.00

ml soln

= 50.0 g soln

δt=t2-t1

= (22.1 – 20.0) °c = 2.1 °c

the heats involved are

heat from neutralization + heat to warm solution + heat to warm calorimeter = 0

q1+q2+q3=0

nδh+mcδt+cδt=0

0.0175 mol ×

δh

+ 50.0 g × 4.184 j·g⁻¹°c⁻¹ × 2.1 °c + 279 j°c⁻¹ × 2.1 °c = 0

0.0175 mol ×

δh

+ 439.32 j + 585.9 j = 0

0.0175 mol ×

δh

= -1025.22 j

δh=1025.22j0.0175 mol= -58 600 j/mol = -58.6 kj/mol