A chemical engineer is studying the rate at which a specific solid reactant dissolves in a solvent. The mass of the remaining reactant, MMM grams, is recorded hhh hours after the process begins. The relationship is modelled by the equation
log10M=−0.0583h+1.9030≤h≤24 \log_{10} M = -0.0583h + 1.903 \quad 0 \le h \le 24 log10M=−0.0583h+1.9030≤h≤24Show that this equation may be written in the form
M=abh M = ab^h M=abhwhere aaa and bbb are constants to be determined. Give the value of aaa to the nearest integer and give the value of bbb to 3 significant figures.
Use the model to predict the mass of the reactant remaining after 24 hours. Give your answer to 2 significant figures.
104 exam-style questions on OCR (MEI) A Level Maths 1.8 Exponentials and Logarithms, covering 1.8.1 The function y = a^x, 1.8.2 Convert between index and logarithmic form, 1.8.3 Logarithm as inverse of exponential, 1.8.4 Laws of logarithms, 1.8.5 Values of log_a a and log_a 1, 1.8.6 Solve equations of the form a^x = b, 1.8.7 Reduce y = ax^n and y = ab^x to linear form, 1.8.8 The function y = e^x, 1.8.9 Gradient of e^kx (A-level only), 1.8.10 The function y = ln x, and 1.8.11 Exponential growth and decay. Each one has a worked solution and a mark scheme showing where the marks go.